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I 




No. 113 






FM 






K^ to*™** 

, 5 . *"> "HZ 




equency Synthesis ■ 

tith a single crystal! I 



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Receiver: Sensitivity: SINAD 5uv for 12db, 1uv provides 20db quieting. • Adjustable 

squelch* Modulation Acceptance: FM wideband (narrow band available) -Type: 
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3^C^-C3--A.ZIISrE 



#113, February 1970 



Features 

2 Never Say Die 
6 Modulated Vibrator Hash 
10 Letters 
16 Leaky Lines 
22 Radio Amateur News Page 
134 Propagation 
138 New Products 
142 Caveat Emptor 
146 Advertisers Index 

Readers' Double Bonus 



STAFF 

Publisher 

Wayne Green WB2IMSD/1 

Managing Editor 

Ken Sessions K6MVH/1 

Advertising 

Diane Shaw 

Production 

Roger Block 
Phil Price 
Jane Tracey 
Jeanne Caskie 
June Trasky 
Whitney Tobias 

Art 

Sill Morello 

Wayne Peeler K4MVW 

Circulation 
Dorothy Gibson 

Comptroller 
Joe LaVigne 

Propagation 

John Nelson 

WTW Editor 

Dave Mann K2AGZ 

Books 

Bruce Marshall 



Contents 



■ ■ 



»■ ¥ * * 



.W2FEZ 



K9LGH 



WA9HES 



K1AOB 



WA9EHE 



W1EMV 



W2EUP 



»••**.. 



, W6ZCL 

.K6MVH 
, W6TEE 

W2IMSD 
W2AOO 
• I1SLO 



14 Fascinating Fundamentals 

The Terrible Jar at Leyden 
24 18 in. Dipole on 15 Meters . . . 

February Fool article? Heh, heh! 
30 High Performance Converter for 6 

73 drags its heels into the 70's with a tube. 
36 From Breadboard to Printed Circuit - The Easy Way 

And it is easy, for once. 
40 The Camper- Mobile and Portable 

Enradioifying the VW bus, 

43 So You Think You Have Troubles? .,„ 

Cutting blind ham's antennas for fun. 

44 Frequency Synthesis - The Modern Way 

Special book-length feature for FM fiends. 
72 Encoding and Decoding in FM Repeaters 

An exercise in FM esoterica. 

Part I. Encoders for Subaudible, Tone-Burst, or 
Whistle-On Use 

Part II. Tone Decoder for Remote Switching 
Applications . . . . . 

Part III. Setting Up the Tone-Burst System 
84 How to Visit Foreign Countries 

Using ham radio to make travel funner. 
86 The DX-35 Revisited , ...... 

Exciting development for chirp haters. 
88 Panoramic Receiver for VHF 

For 2 meter busy bodies. 

96 Variable-Impedance Mobile Mount • * W1EMV 

Out, damned reactance! 

97 Lossy Transmission Lines 9m . m KH6IJ/1 

A shorty short. 

98 Extra Class Study Course, Part 13 .,. 

RTTY, FSK, filters and other such trivia. 
115 New Linear IC's for the Ham , 

Cheap— new— hot— have fun, 
126 The Glop Will Get You If You Don't Watch Out! . . 

Watch out! 

130 DX as seen by ■ , . 

Cartoon feature. 

131 The Micromitter 

World's cheapest rig. 
134 A Simple Integrated Circuit Q Multiplier 

Makes the CW band ten times wider, 

137 Quick Stop and Reversing for Antenna Rotors . .PY2AUC 

Whipping antenna whip. 



73 Magazine is published by 73, Inc., Peterborough, New Hampshire 
03458. Subscription rate: $12 for three years, $6 for one year. 
Second class postage paid at Peterborough.* X. II.. and at additional 
mailing offices. Printed in Pontiac, III Entire contents copyright 
1970 by 73, Inc.. Peterborough, N,H, This issue is all right, but 
wait until you see the Giant March Surplus Catalog Issue next 
month! If you dig surplus, stand by for mind boggling. You don't 
like surplus? OL 



*•■**• 



* * * , 



**#■•*« 



■ V 



.Staff 



WA4KRE 



W2ELU 



W6EIF 



WA3GGH 



W2EEY 



FEBRUARY 1970 




EDITORIAL BY WAYNE GREEN 



Crowded Bands 

If you, too, have been involved with amateur 
radio for some thirty years, I think you'll have to 
agree with me that one of the big all-time 
complaints has been QRM. Even those with sixty 
years of hamming under their belts will tell you 
that from the first day of their operating, QRM 
was murder. 

Since, in practical application, QRM can be 
largely avoided, I suspect that most of the true 
sufferers from the condition are masochists, un- 
duly stubborn, or perhaps just not too swift. At 
one time in .our history amateur radio was rather 
well known to the general public, though the image 
they had was one of young boys staying up all 
night in attics, I'm not sure that even that image is 
better than not having one at all, which is about 
the shape we're in these days. 

Green's Law 

If you insist on forcing amateur radio to fit 
your convenience, you may be a sufferer from 
QRM. The evening hours and weekends are the 
most convenient, so that obviously is when there 
are the most stations on the air . . . and the most 
QRM. These are prime times for developing a 
mental hernia trying to get a short ragc|iew on 
20-40-80, Meanwhile, up on 2 and 6 meters, this 
heady peak of activity will, in many parts of the 
country, give you a choice of two stations to 
contact instead of one. Green's QRM Law No. 1 
(an extension of the Finagle Principle) tells us that 
if there are just two contacts on a band, they will 
probably be just about on the same frequency and 
will be QRM'ing each other. 

The RTTY gang can be heard typing up a storm 
with little interference, and, lonely of the lonely, 
the Extra Class CW ops can be heard during peak 
operating hours all huddled near one frequency 
down in their exclusive bands. 

If you are too stubborn to head for the wide 
open spaces of 2 or 6 meters, don't dig typing out 
your contacts, and don't cotton to the untram- 
meled higher frequencies on 10 meters, then 
perhaps you could bend to the extent of changing 
your operating hours a bit? I may be ruining a 
perfectly good thing for myself by telling you 
about this, but the bands are almost empty in the 

early mornings. That's when you'll heat me operat- 
ing. 



Generally Fin in bed by 10 p.m., which means 
that along about 4 a.m, or so my eyes open up and 
1 either lie there staring at the ceiling or else get up, 
get dressed, and head for the office, a twisty 
10-mile drive through the New Hampshire hills. 
After fixing a quick breakfast I head for the rig and 
see what is doing. The signals are few, but the band 
is most certainly open and the contacts are 
generally free of QRM. In winter I can usually 
work just about anyone who happens to be on the 
air in Asia, the Pacific, South America, Antarctica, 
and even Europe, 

Don't Follow the Pack 

A little trick 1 learned the hard way nets me a 
lot more DX than the average operator, Now and 
then you will hear me in a pileup, but most of the 
time you'll hear me starting pileups, not continuing 
thern. 

After listening to the gangs of operators trying 
to get through to rare spots, you may get the 
erroneous idea that the op in the rare spot has it 
easy -any time he gets on he is loaded with fellows 
trying to contact him. It doesn't work that way* 
This fellow has a good deal of frustration because 
he is in an out-of-the-way spot. 

The problem is that when Europe is coming 
through to the States, almost every beam is 
pointed at Europe. The fellow r down on a small 
Caribbean island can call his fool head off and no 
one will hear him. I remember one particularly 
frustrating time. I had just received my license to 
operate as VR2FD in the Fiji Islands and I fired up 
on 20 sideband. The band was hopping . . . this was 
going to be fun. I heard Dorothy K2MGE in a 
roundtable with some other friends and I called in. 
Nothing. I tried breaking. Nothing. After a half 
hour of trying to break between every leg of the 
roundtable, I heard Dorothy say she thought she 
heard someone trying to break the QSO. My relief 
was short-lived. The next station came on and 
dismissed me with the remark that whoever was 
trying to break in was not cutting the mustard. 
They never did stand by for me. I tried up and 
down the band for another hour, calling CQ, 
answering CQs and trying to break in on friends. 
The VRs that were in the shack with me explained 
that it is always like that, Everyone has his beam 
pointed toward Europe and there is little chance of 
getting through. 



73 MAGAZINE 



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A single tuned output amplifier designed to 
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Eventually I snagged a KH6 and a couple of the 
more alert W6s heard the contact. Suddenly there 
was a pileup and 1 was busy handing out contacts 
as fast as I could, You could almost hear the 
rumble of a thousand beams turning all over the 
U.S. 

Now, when I get on the air from home, I seldom 
point my beam along with the crowd. If they are 
working Europe I swing my beam around and call a 
CQ toward Asia or the Pacific, If they are working 
the Pacific, then I call for the Indian Ocean or the 
Mid-East. These directional CQs work for me, Just 
yesterday 1 contacted VK6GK mobile (VK6 is the 
antipodes from up here), 9V10H, and VU2GE. 
The VU was running 15W of SSB, by the way. 
More often than not, a directional CQ like that will 
bring in something rare, giving you a contact that 
you otherwise might have to spend hours working 

for, fighting the pileups, 

* . . Wayne 

^ ^^^^^^^^^^^^^—^^^^^^^^^^^^^—^^^ 

Gentlemen: 

With regard to your Christmas photo in the 
December issue: 

We've looked at the picture-examined the scene, 
Which is quite reminiscent of Mad magazine. 

We've paid close attention and Lin Green looks nice, 
And so does Dot Gibson— ditto Phil Price. 

Walt Manek looks sad through a grin that's excessive. 
Is that what you call a Manek depressive? 

Horray for Diane who in mini looks racy 

And hello there to Roger and Don and Jane Tracey. 

Hi, to Joe, Jeanne and Wayne-the rest of the cast- 
And now for the best which we've saved for the last. 

Your gang sure appears like a fun-loving group 
And we quite hate to throw an old fly in the soup 

But all through the years, in hamming, in life, 
In all of the good times, and all of the strife 

Past all tribulations-past winnings and losings 

Past days being sober, and days filled with boozings, 

You can torture us, mangle us, freeze us or fry us— 
There can't be a girl named Whitney Tobias f! 

Jules E. Blitz 

7934 Winterset Ave 

PikesvilleMD 21208 

Dear Reader Jules: much thanks for your poem. 
It has spiced up the air at our magazine's home. 
As to your comments about Lin and Dot t 
We agree with you fully—they said "Thanks a lot." 
Phil Price thought it funny— he shed a small tear, 
And our Manek depressive is no longer here m 

As for Diane , well she accepts, with a wink, 
And Roger and Jane say "Hi t JuJes," 1 think. 
Our Joe and our Jeanne send 73 f s t 
And Wayne f our big chief t completely agrees. 

Yes, we are a fine bunch, and we do have much fun t 
But your fly in the soup is such a bad pun. 
For in truth and in friendship (I'm not being pious), 
There is truly a girl named Whitney Tobias, 

. . .Diane Shaw 



73 MAGAZINE 



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AIM 

EDITORIAL 
BY K6MVH 
KEN SESSIONS, 



JR. 



Why This issue of 73 
is Dedicated to WA8UTB 



This is an obituary. 

An entity that lived fast and hard and well has 
passed. This living thing was FM Magazine. For me 
it was a promise unfulfilled- For Mike Van Den 
Branden it was a dream turned nightmare. For a 
world of new people -the repeater men, the two- 
way hams, tiie FM pioneers- the death of FM 
Magazine was the loss of something that was 
uniquely their own. 

Mike Van Den Branden WA8UTB was the 

originator of the magazine, hack in February 1967. 
He put out a sheaf of duplicated papers and called 
it FM Bulletin. Everything seemed right. There was 
a. general turning to FM on our VHF amateur 
bands that was to grow beyond everyone's belief. 
And the Bulletin was to beeome the widely 
approved and unanimously accepted voice of this 
new and expanding group- 
Matching the contagious popularity of the 
mode, the publication expanded too . , * until it 
seemed the bulletin- turned-magazine would bust 
apart. It went from duplication to lithography. 
And within months it was a well dressed slick with 
four-color cover and professionally prepared inter- 
ior that could stand abreast with the best of the 
well established old-time pros. 



I was editor of this magazine, and shared the 
ownership with Mike until it nearly broke my 
back, When I gave up, he carried on, assuming 
responsibility for a financial burden that would 
make Rockefeller cough. 

Oddly, Mike Van Den Branden was not in the 
publication business for the money. He was one of 
those rare, one-in-a-lifetime types who follow a 
dream because of the dream. Mike believed in FM 

as a communications mode. And he believed his 
magazine filled a definite need. This is not to say 
that Mike would not have been pleased to see his 
"baby" turn a profit; but he was not once 
discouraged by the fact that it never did. 

And Mike was always willing to bear the 
financial brunt of new ways by which his baby 
could be improved. If you happen to be one of the 
very very few foriunates who have a complete 
library of FM, you know the metamorphoses that 
characterized the 3-year lifespan of FM Magazine. 

This is the end of the obituary of FM Magazine. 
But it by no means marks the end of the Mike Van 
Den Brandens, So maybe a toast is in order: 

Here's to the dreamers. 



Buffalo Hams Influence 
Rulemaking in Canada 



The members of the Buffalo Amateur Repeater 
Association are to be congratulated; for these 
individuals, who spent many long and arduous 
hours drafting a detailed and comprehensive peti- 
tion to the FCC concerning the operation of 
repeaters in the VHF amateur hands, have achieved 
at least a degree of success. The efforts of Gil 
Boelke W2EUP, Francis Stengel WB2GUG, and a 



handful of others of the BARA organization have 
not gone unnoticed. Some time ago, Canada's 
regulatory agency, the Department of Communica- 
tions, sought guidance in laying out a plan of rules 
for prospective Canadian repeater licensees. Using 
the Buffalo petition as a foundation from which a 

set of realistic regulations could evolve, the DOC 
recently published a tentative mandate that will 



73 MAGAZINE 






1970 ISN'T ALL THAT'S NEW .. . 

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serve as "interim regulations 1 until such lime as 
permanent rules for amateur repeaters are passed 
into law. 

Of the mandate's seven points, at least four had 
been put forth in the famed Buffalo petition, and 
several of the others were unofficially advocated 
by BAR A representatives in letters drafted after 
the petition was originally filed* 

The points of significance to repeater owners 
are: 

• Licensee will be responsible for TECHNICAL 

operation of the repeater, including ultimate 
control over any amateur's access (or 
the access of a restricted group). 

• Licensee will maintain a TECHNICAL log 
Showing malfunctions, servicing data, on-the- 
air tests, etc. (This precludes the necessity for 
running a continuous tape log of operation, 
presumably, and is the essence of the Buffalo 
petition.) 

• Repeaters will identify at one-minute inter- 
vals by transmission of the repeater call sign 
at reduced amplitude. 

• Links are to be in the frequency range above 
220 MHz, but they are exempt from the 
aforementioned identification requirement. 

• The licensee is required to put a three-minute 
automatic shutdown transmitter on each of 
his remotely controlled transmitters. And it 
must be rigged in such a way that only the 
licensee can turn the transmitters on again 
once they are shut down. 



These rules are a step in the right direction, and 
they serve to show that the Canadian government 
is on its toes with respect to what's happening in 
the amateur world there. But there is one aspect of 
the rules that has frightful implications. I can only 
hope it is a mistake in wording, because it can serve 
no useful function of itself and can only result in 
making repeaters in Canada less utilitarian for the 
many users. 

The rule I am referring to, of course, is the last 
one cited above. The mandate specifically states 
that when a repeater is timed out at the end of a 
three-minute period, it must be reenergized by the 
licensee only. In practice, virtually all repeaters- 
both in the LLS* and in Canada— are already 
equipped with such timers; when an incoming 
transmission exceeds a duration of three minutes, 
the repeater (and usually the links) shuts down. 
But reactivation is typically automatic; that is, 
when the longwiiidcd individual drops his carrier, 
the repeater can be energized again by the next 
incoming signal. 

Ostensibly, the Canadian ruling was put forth 
to assure technical control under all conditions. 
But the DOC should be made aware that such 
control could be assured in a variety of other ways, 
nearly any of which would result in a more useful, 
reliable system. For example, the licensee could 
transmit a control signal thai would positively 



(rather than passively) shut down the transmitter 
when such shutdown is warranted. Or he -or 
anyone else using the repeater— could keep the 
system shut down by transmitting a continuous 
low-power carrier on the input frequency until 
positive control was effected. 

There are a variety of means for achieving the 
same end. But the finality of automatic timeout 
suggested by the mandate does not seem to be in 

the best interest of the amateurs who will depend 
on the reliability and dependability of a repeater 
that will frequently be shut down by individuals 
who can't seem to turn themselves off after 
2,999999 minutes of talking. 

An interesting sidenote: QST published a short 
note about the Canadian doings in the December 
issue. Several ARRL directors were credited, but 
there was no mention of the effort expended by 
the Buffalo group. I consider this a bit odd, 
considering the fact that the ARRL has had a copy 
of the Buffalo petition since the time it was filed, 
back in 1967. 



Repeater Petition to 
Get Docket Number 

A repeater rulemaking petition was submitted 
to the FCC on December 3. 1969, and is currently 
undergoing processing so that a docket number can 
be assigned. The petition is too lengthy for 
reprinting here, but here is the essence of it: 

1. An amateur repeater is officially recognized 
and defined. 

2. Repeaters to be made legal on all frequencies 
where A0 is authorized. 

3. Timed shutdown is required after long non- 
use periods. 

4. Repeaters can be turned on from the fre- 
quency of operation provided that UHF 
control is capable of overriding such turn-on, 
when necessary. 

5. Repeaters can be "unattended," since shut- 
down is automatic when repeater is not used. 
It can thus be assumed that the repeater is 
being monitored (from the frequency of 
actual use) when it is on. The petition seeks 
to dispense with "UHF control" monitoring 
in favor of the "on-when-used, off-when- 
not-used" approach, w f hich is essentially 
"unattended" operation, but with a realistic 
and workable twist. 

6. Repeaters should not be logged in the con- 
ventional sense. A log would consist of a few 
basic particulars and would be filled in only 
when the remote repeater is visited, serviced, 
or modified. ' 

7. Repeaters should be identified at 3-minute 
intervals, and the ID can be nothing more 
than the repeater call letters, in Morse code 
or voice. 

(continued on next page) 



3 



73 MAGAZINE 




...WANT TO GET IN ON THE ACTION i 



9 




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through the repeat- 
er's "dead spots/' 
. . .The perfect dri- 
ver for that final on 
the hill! 




i 



i 



10 GRAHAM ROAD WEST • ITHACA, N. Y. 1485 
TELEPHONE AREA CODE 807-257-2424 




The SAROC Funfest 

In case it's slipped your mind, time is running 
out for those of you who haven't made advance 
reservations for SAROC, the Stardust Amateur 
Radio Operators* Convention, to be held on 
February 4 - 8 at the Stardust Hotel in Las Vegas. 
The SAROC funfest has been getting bigger by the 
year, and indications to date are that this year will 
top all previous records. 

Tor the nonteetotaling among you, SAROC will 
offer a number of advantages for you to mooch 
free booze; cocktail parties are being hosted by the 
magnanimous managements of Swan, Galaxy, and 
Ham Radio, 

National FM Convention. Ham FM'ers should take 
particular note because SAROC serves as an oper- 
ating base for the annual national FM convention, 
Tom Burford W7TDQ is the principal representa- 
tive for the KM portion of the shindig; and if you 
drop him a card, he can give you the details on the 
FM programs slated for this year (which, incident- 
ally, marks the third annual national FM conven- 
tion to be held in conjunction with SAROC). 
Tom's address is 6328 Shawnee Ave., Las Vegas, 



At this writing I have no idea as to what the 
agenda is, but I can guarantee that it will be 
interesting. Last year, a national repeater group 
was formed, and national repeater frequencies were 
adopted. There were a few disappointing problems 
associated with FM scheduling last year, but most 
of these were attributable to apathy on the part of 
the hotel management. Switching of SAROC from 
its previous base to the Stardust has solved these 
potential headaches, I hear. 



If you have gripes about 73 or its policies, or if 
you have pet circuits you want to see printed, grab 
me at SAROC. I won't be hard to spot: just look 
for the guy who has the "special deal" on 
subscriptions. 

Reservations. If you don't know how to get your 
reservations or how much money the affair will 
cost, send SASE to SAROC, Box 73, Boulder City, 
NV 89005. You'll get the details back fast 



K6MVH 



FEBRUARY 1970 




Ml — 



advised by my 

ou g >ns < ' t 



wyers that 
3 r o fr 

-*►*■-««*«. .h L>V a»S I— 

n 



I insist that you print ev 
should be boiled in oil ov 



Audible 73s 

Dear Mr. Green: 

Someone mentioned to me the possibility that 
your magazine was being recorded on magnetic 
tape for the use of interested blind persons. If this 
is true, please let me know where I might apply in 
order to borrow these tapes. 

Oliver K. Mrxon W4DJF 
Augusta-Richmond County Municipal Building 

Augusta, Georgia 
Recorded tapes of 73 are available from: 
Science for the Blind 
221 Rock Hill Road 
Bala Cynwyd PA 19004 

Hospitality Notes 

Dear Friend, 

I am very interested in your Ham Hospitality 
scheme and hereby offer my home for any visiting 
hams ? especially Stateside DX. 

My interests are ham radio, organ music* and 
politics (I am a City Counselor, Johannesburg). 
XYL is 45 years old. Her interests are cooking, 
garden, stamps and polities. We have two delightful 
dogs {our children are married and live elsewhere) 
and, apart from two full-time servants, we live 
alone. 

This offer is made in all sincerity- no strings 
attached. Visitors and their children would be 
made very welcome. We love having guests and 
would be offended if any offer of payment is 
made. Reciprocity one day is all we expect. Are 
there any California hams who could house Corrie 
and self over December 1970? I would like to write 
to them. 

Dan Mahony ZS60S 

POBox 1729 

Johannesburg, S. Africa 



Study Courses 

Dear Wayne; 

I hold an Advance ticket, Wayne -thanks to 
your very fine recent series devoted to helping 
amateurs climb the ladder. The exam -which I 
took and passed last week -was a cinch, only 
because I understood every question and could 
answer all with equal comprehension. Any amateur 
who feels he can pass the Advance exam by 
memorizing the ARRL license manual is fooling 
himself. It just won't work. Incident ly t your 
November editorial correctly observed that the 
emphasis is now on SSB and transistors. It should 
be. Needless to say, 1 have accumulated an 
digested your Extra lessons, and this exam, too, 1 
expect to be a breeze (thanks to your very I 
handling of the material). My only problem is m 
code speed, which I hope to bring up to 25 wpm. 

Charles J. Vlahos WB2ICV 
Managing Edi' 
Plant Operating Management 

205 East 42nd St, 
New York NY 10017 

TV! Case 

To the editor; 

The other day I spent some time at a friend 
house, and as I was leaving 1 borrowed five or six 
copies of 73. When I reached home I sat down to 
glance through this magazine and ended up devour- 
ing one issue. It was sheer pleasure to sit down and 
read interesting material, page after page. As you 
can tell, I am sold on 73. 

I believe now is the time to express an opinion 
and ask a question. First the opinion. 

In your February 69 issue of 73, on page 36, is 
an article "$1,000,000 TVI Suit Filed." I read this 
through twice and wondered if 73 was the only 
amateur magazine interested enough to speak out. 
I found five issues of QST, for the months of 
February, March, April, May, and June 1969. I 
could not find one word about this "amateur 
world" law suit. 

Now for the question. Would you please inform 
me of the outcome of this case, and does Grid 
W4GJO have the backing of the amateur popula- 
tion? I hope that this will not pose too much of a 
problem, but I am interested, as all hams should 
be. 

I wonder why, after two years of QST, I never 
wrote a letter; but after one weekend of 73 
magazine, here I am. 

Daniel G. Willis, SSgt, USAF 

CT2AS/WA2BDA 

Box 183, 1605 CAMS 

APO New York 09406 



Help! 

Editor: 

1 would like to purchase or scrounge, whichever 
is applicable, RCA publications: 
RCA Silicon Power Circuits- 
Application sheet SMA36. 
Application sheet SMA40. 
Also, any data re lCs used in FM i-f strips at 
10,7 MHz and 455 kHz, narrowband (±5 kHz) 
quadrature detector, etc. 

John C. Meyland VK3AMI 

Wangaratta, Vic* 

Australia 3677 



As a result of the exposure accorded the case in 
73, the defendant has received assistance from a 
number of sources: From the ARRL, he received 
(without strings attached) a mimeographed list of 
suits involving tower cases; and from fellow ama- 
teurs, he has received a great many cash donations, 
which have been used to assist him in paying for 
the burdensome legal fees. Grid Gridtey W4GJO, 
the defendant, tells us he is extremely grateful for 
the publicity m 73 and the support from within 
our fraternity. He reports that the suit has been 
dropped under a mutual agreement. 



10 



73 MAGAZINE 




Self-Appraisal 

Dear Mr. Green: 

Having just gotten my October issue of 73 and 
having just read the letters column 1 want to make 
my opinion heard. We want to encourage new 
blood in the hobby. Introducing new people to the 
phone bands is most certainly not the way to do it, 

We want to show them our better side. But the 
question is, what is our better side? I have yet to 
find the better side of ham radio {better side in my 
eyes). The phone bands are made up of hams that 
couldn't copy 3 words a minute of code, discour- 
teous people, old people that scorn the "new 
breed" of appliance ops, and young people, who 
scorn the oldtimer-a lot of good ops and fine 
personalities- The CW bands are made up of dead 
segments where you can call for hours without a 
contact, segments so crowded that no one can 
copy anyone, and you have essentially the same 
crowd thinking much the same way as phone men 
with either the man thinking about getting one of 
those higher grade licenses and trying to get up his 
code speed, or you have the group that think the 
phone men are all lids that can't copy a word of 
code and are only slightly better than CB'ers. 

The lure for many newcomers is the old farce 
of communicating with amateurs in foreign coun- 
tries. In two years I have had calls from 18 
countries. But I haven't communicated with them, 
Tve communicated with three countries (one was 
an American working in a foreign embassy). I 
started in ham radio to find out what it is really 
like in Iron Curtain countries, Oh, you can talk to 
these countries. You usually have a long QSO of 
maybe 30 seconds if someone isn't continually 
tuning up on you. Some people are lucky enough 
to be able to communicate with foreign stations* 
They are usually the ones with 2 kW linears, big 
multielement beams on tall towers, with expensive 
gear. 

And we really expect to compete with CB and 
SWLing? W4PZS is certainly correct in saying 
"they have divided the amateurs/' They pushed 
incentive licensing through, even though there was 
much opposition (and much more apathy). 

1 am having much trouble saying exactly what I 
mean. Just the same, I think amateur radio is 
awfully lucky to get any newcomers that keep at it 
and get their General (or any of the others). After 
all, what does amateur radio really have to offer a 
newcomer? Many of the statements that might 
have once been true about amateur radio don't 
seem to even applv to amateur radio now. 

Jtm Pruitt WA7DUY/AFB7DUY 

111 Hirschbeck Heights 

Aberdeen WA 98520 

New FWTer 

Dear Wayne, 

I have decided to become a ham and I am 
studying for a Technician license. I plan to go on 2 
meters FM, but 1 am having trouble locating an FM 
unit I hope they axe not expensive! I am not in an 
ideal antenna location and might have trouble 
mounting a large array. I hope I can get good 
distance with a less expensive antenna, I have heard 
of hand-operated rotors from the old days and if I 

could find such a system, it would be practical 
since my shack would be in the attic. 

I hope there is enough activity on VHF FM so 
that I can get some good QSOs- 1 started interest in 



FM when I heard so many 80 meter AM hams talk 
about such 2 meter nets* 

My main interest would probably be rag- 
chewing and possibly DX (especially when the 
aurora kicks up, as it sometimes visibly does up 
here). I have most of the technical part of the 
exam wrapped up and the code speed is coming, 
slow but sure. 

Rae Shortt 
Lots of FM gear available. Check the Double Bonus 
subject index in the back of this 73. 

More Backlash 

Dear Wayne; 

Your recent thorough treatment of the incen- 
tive licensing problem, relating it to the miscalcula- 
tions emanating from Newington, were excellent. 
Keep up the good work. 

I detect a groundswell of considerable magni- 
tude on this matter, with everybody giving up on 
ARRL as the source to look to. In this state hams 
are writing directly to the FCC to lodge their 
protests. 

I suspect that Newington will change its mind 
eventually . . .as soon as ARRL revenue drops off 
and salaries must be cut* 

Louis R. Huber, President 

Northern Films 

Box 98 Main Office Station 

Seattle W A 98111 

Still More Backlash 

Dear Wayne: 

It is not often I write letters, but after reading 
so many comments in your magazine and also in 
another magazine I thought I would also comment. 

I did not think the ARRL's incentive license 
plan would be worth very much and it seems I was 
right. I don't know what the extra education 
necessary to get the Extra Class license is going to 
do for the greater number who get it. If they are 
going to follow a commercial radio future, it might 
be of value; otherwise, I think at least 99% go out 
and buy a shack full of equipment as soon as the 
license comes. The ARRL representatives at the 
Dayton Hamvention admitted the reason there was 
not too many homebrew projects in QST any more 
is there are no homebrewers any more. 

Why should there be so many classes of 
licenses? I think after a Novice license any citizen 
with a capability of 5 or 6 wpm of CW and the 
knowledge necessary to operate properly should be 
able to get a license to operate anywhere on any 
band available to hams. When you go for a driver's 
license it would be the same to have the instructor 
tell you that with your limited mechanical know- 
ledge, you could not drive a Cadillac: only a VW 
until you could upgrade your knowledge. The 
temporary permit to drive is the same as a 
Novice-and after you prove you can obey the 
driving laws, you get your license to drive on any 
highway in any auto you choose to buy. Why 
should not any ham, having obtained a regular 
"license/* be able to go into a store and purchase 
any piece of "ham" gear, then take it home and 
put it on the air? 

The sooner something is done to allow r every 
citizen the rights he is entitled to in this country, 
the sooner we shall have peace. 

Harold D* Mohr K8ZHZ 

5670 Taylor Road 

Gahanna OH 43230 



FEBRUARY 1970 



11 



Manitoba Centennial Award 



Dear Sir, 

A copy of the starting date, rules, etc. for our 
1870-1970 Manitoba Centennial Award is en- 
closed. Wc would appreciate it very much if you 
would publish this: 

The Amateur Radio League of Manitoba wit! 
present certificate awards to amateurs submitting 
proof of the requisite contacts with amateur radio 
stations in Manitoba. All contacts must be made 
after Dec. 31, 1969. Contestants must accumulate 
100 points. W/K, XE, and VE stations receive two 
points per contact; all other stations receive five 
points per contact (A contact consists of exchang- 
ing signal reports.) Contacts may be made on 
different modes on each band, but cross-mode 
contacts are not allowed. 

Two different members of the Amateur Radio 
League of Manitoba will be designated "Bonus 
Hams" each month. Contacts with these stations 
will be worth double points. 

Contestants should send a copy of their log and 
two IRCs to: 

Mr, J. N. Knowles VE4JK 

PO Box 365 
Carman, Manitoba, Canada 



Reciprocal Trade 

Dear Mr. Wayne: 

I am an Indian radio amateur with call VU2JEZ 
and a 3 yr subscriber to 73. I am a high school 
student and India's youngest radio amateur* 

Well, it was a sort of impossible urge that made 
me write this letter to you, hoping that v OU will 
understand and sympathize with nry problem: 

In India out of the 500-odd amateurs, all 
depend on war surplus and homebrew equipment. 
The maximum amoufvt an Indian ham spends on a 
rig is $50* $75. 

I have built my transmitter myself, and I tried 
to get a BC 348 working (which I had bought on 
the junk market). But all efforts failed. Wei C now I 
have saved about S 1 00 after two years. I got my 
ticket 6 months ago, and Vm still not on the air. 
What I want to propose is this: You ask some other 
amateur to send me a ham receiver (used will do) 
and I shall send him Indian goods (antique carv- 
ings, paintings, embroidered shawls, etc). I make 
this proposal because import restrictions do not 
allow cash payment. 

Thus, he can send me this receiver as a gift and 
I can send what he wants as a gift! 

Or, if he prefers, I can give the money in Indian 
currency to any of his relatives in India or the 
USIS in Bombay, 

I know I have said what I have to say rather 
clumsily but, I sincerely hope that you understand 
my situation and will help me out by dropping a 
hint to some of your vast multitude of U.S. 
amateurs. 

1 shall certainly remember you all my life long 
for having helped me to get started in amateur 
radio. 

Gopal Kamat (VU2JEZ 

Municipal Soc,A/8, L. J. Road, 

Mahim Bombay 16 INDIA 



Two Cents' Worth 

Dear Wayne, 

A couple of comments and opinions on articles 
in the December issue: 

1. Topographic maps now cost 50*/ each. Infla- 
tion has hit the U.S. Geological Survey too. 
The Bureau of Land Management has some 
attractive maps of many areas of the West; 
available free (the price is right) from BLM 
offices located in state capitals. These have 
almost as much detail as the topographic 
maps. 

2. The Swan TV2*s instruction book contains a 
drawing of proper connections for a switch 
to avoid cubic changing from the TV2 and its 
exciter. It even gives the Swan pari number. I 
got one of these, plus two cables with the 
Jones plug already attached from them and 
threw together the switch -without resorting 
to coaxial relays (no pain, no strain). Only 
problem was changing one wire on the plug 
for the low voltage de for the PC hoard. The 
unit would I M on 2m SSB: however, a new 
zener diode and more suitable crystal 
(factory-installed at no charge) took care of 
it. I even power a little 2m preamp from this 
line. 

Paul Schuett WA6CPP 

14472 Davis Road 

Lodi CA 95240 

Boos and Hisses 

Dear Wayne: 

I take umbrage to W4NVK*s article in the 
December 73, I have yet to align or service any 
piece of ham equipment that I could not gel at 
least 50 dB suppression of the carrier. Second, 
there is no way, under any circumstance, that bi 
shift on finals can cause an increase of carrier 
content on the signal. For the edification of Mr. 
Dusina, the author, I service and repair amateur 
goodies in the Detroit area. My operating bench is 
loaded with about $4,000,00 worth of equipment. 

I paid for these items by repairing equipment for 

II meter operators with General class or higher 
licenses. Only last Sunday, a fellow brought" his 
transmitter over because he could get only 40 dB 
of suppression and while I checked, he yakked 
about how many years he was operating and no 
sense doing this or thai to his rig, etc. While he 
talked, I removed 22 more dB of carrier from his 
set and S 35.00 from his wallet. Anyway, if Mr. 
Dusina will ship prepaid his bucket of bolts to me, 
I'll remove his residual carrier free of charge. 
Otherwise, let him properly center the audio in the 
bandpass (then a $2.00 mike won't sound so good) 
and put an rf probe on the antenna output jack-lo 
and behold, he will have 60 dB of suppression. 
Next, his remark that a 100W CW signal is 200W 
SSB is erroneous. A transmitter cannot put out 
more power than it has been loaded for without 
doubling plate voltage. If you don't believe that, 
load your transmitter fully on CW, and with a 
scope, note the height of the solid rf display. 
Switch to SSB and the peaks will not exceed the 
CW. 

Paul Kirsch WA8ASQ 

14158 Foch 

Livonia Ml 48154 

(Continued on page 128) 



12 



73 MAGAZINE 




The GT-550 




GALAXY 



Based on the proven Galaxy V Mk 3 design ... the GT-550 comes on stage with an 
entirely new look. And under this beautiful new exterior Galaxy has packed 550 

watts . . . the highest powered unit in its field. Henry Radio, always the first with 
the best, is proud to introduce this fine piece of equipment along with an equally 
fine line of accessories. 

Come on in, look them over. Or write or phone. Well send you detailed 
specifications. 



GT-550, 
AC 400, 
G-1000, 
RV-550, 

RF-550, 

SC-550, 



550 watt transceiver 

AC Power Supply, 110/230 VAC, includes cables 

DC Power Supply, 12/14 VDC, Neg. Ground 

Standard Remote VFO provides dual frequency 

control for GT-550 only 

3000/400 watt Wattmeter /Antenna Selector 

(Available after April 1) 

Standard Speaker Console, 5x7 speaker 8 ohm, 

(AC-400 will mount inside) 



$550.00 
$ 99.95 
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Henry Radio kas a great antenna package program . . . big savings. Write for literature. 

EASY FINANCING • 10% DOWN OR TRADE-IN DOWN • NO FINANCE CHARGE IF PAID IN 90 
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credit toward the purchase of NEW equipment. Write for bulletin. Export inquiries invited. 



TED HENRY (W6UOU) 



BOB HENRY (W0ARA) 



WALT HENRY (W62N) 



fflMM/S 

M idIT f FP . r . .. . m ITi - - _»t 



11240 W.Olympic Blvd., Los Angeles, Calif. 90064 213/477-6701 
931 N. Euclid, Anaheim. Calif. 92801 714/772-9200 

Butler, Missouri 64730 816/679-3127 

"World's Largest Distributor of Amateur Radio Equipment" 



FEBRUARY 1970 



13 



— 



mmmmmmmmmmm^m 



Fascinating Fundamentals 




w. Edmund Hood W2FI 
223 Pullman Ai 
RjQvhesiet NY I 46 IS 




mmmmmmi 



Part IV- The Terrible Jar At Ley den 



The year was 1745, and scientific circles 
were all agog over that strange force called 
electricity. In England, several decades earl- 
ier, Francis Hawksbee had built an electric 
machine which produced unprecedented 
quantities of this mysterious power, and 
Stephen Gray had demonstrated that the 
power could actually flow from one sub- 
stance to another. Two Frenchmen, Francois 
de Cisternay Dufay and Abbe Nollet had 
discovered two different kinds of electrical 
power, each capable of neutralizing the 
other. 

Many theories had been offered as to the 
nature of electricity. The most popular was 
that it was some kind of an invisible fluid, 
(That's why we refer to it today as "juice.") 
All in all it certainly was an exciting time. 

Ley den is a small town in Holland, about 
fifteen miles north of Rotterdam. It was 
there, during these exciting times, that a 
distinguished scientist, van Musschenbroek 
set out to find a way to collect this electric 
fluid. Could it possibly be collected in a bot- 
tle? With the aid of a pupil named Cuneus, va n 
Musschenbroek connected his Hawksbee 
electric generator through an iron chain to a 
gun barrel. Another chain hung from the 
other end of the gun barrel. Van Musschen- 
broek had his student hold a jar so that the 
loose chain dangled into it. After the 
machine had run for a while, the jar was 
found to have an electric charge, but there 
was no fluid present. Van Musschenbroek 



then decided to put some water into the jar. 
He knew that electric fluid seemed to flow 
most easily through wet materials. 

Soon they were set up and the machine 
was running again. Cuneus held the bottle at 
one end while the professor turned the 
generator. This time they carefully watched 
the level of the water, hoping to see evidence 
of more fluid, Time passed, and the liquid 
level in the jar was unchanged. The experi- 
menters were discouraged. Van Mus- 
schenbroek stopped the machine, and 
Cuneus reached up to disconnect the chain. 

Suddenly Cuneus dropped the jar and 
seemed almost to fly backward. The profes- 
sor rushed over to his student, Cuneus was 
pale and scarcely breathing. He had received 
a shock such as no man had ever felt before. 
After his student recovered, Musschenbroek 
wrote of his "terrible" experiment to a 
colleague at the French Academy. He ad- 
vised that no one else try it. Naturally, 
everyone else did. 

At the same time as van Musschenbroek 
performed this nearly fatal experiment, the 
Bishop of Pomerania, E, G. von Kleist did 
essentially the same thing with similar re- 
sults. He failed to publish his findings 
through acceptable channels, that is, by 
writing of them to a university or other seat 
of learning, so the credit went to Musschen- 
broek. The device was named the "Leyden 
Jar." 

The scientists didn*t realize it at the time, 



14 



73 MAGAZINE 






but they had actually made a capacitor. The 
water served as one conductor and the 

student's hand as the other. The glass was 

the dielectric. It was later to be improved by 
using foil conductors, but in the meantime 
the water was thought to be essential. The 
scientists believed that the cool water con- 
densed the electric fluid, and the Leyden Jar 
was nicknamed a "condenser." That term is 
still used to this day. 



CHARGE 



ZL 



± GROUND OUTER FOIL 




The home experimenter can make his own 
Leyden Jar quite easily. All that is needed is 
a peanut-butter jar, some aluminum foil, and 
a small length of chain* The inside and 
outside of the jar are lined with foil up to 
within Yz-inch of the top. The chain is 
soldered to the center of the cover, and 
hangs down into the jar. It should be long 
enough that a couple of inches rests on the 
foil on the bottom. 

To charge your Leyden Jar, the outside 
foil should be grounded. You can use a 
battery, high voltage supply, or you can 
charge it up by static electricity. Simply rub 
a glass rod with a piece of silk and touch the 
rod to the cover of the jar. If you do this 
enough times, the jar will accumulate quite a 
charge. 

Now, since some clod might be stupid 
enough to try it, don't connect it to a 
lightning rod. The early scientists who tried 
that seldom lived long enough to publish 
their results. 



I once made a capacitor to demonstrate 
the principle to a group of Boy Scouts, using 
a roll of waxed paper and a roll or two of 
aluminum foil. Begin by unrolling four or 
five yards of waxed paper onto the floor. 
Place a strip of aluminum foil on top of this 
so that the foil overlaps the paper by a few 




inches on one side, and the paper sticks out 
an inch or so on the other side. Lay a strip 
of waxed paper on top of this, exactly 
covering the first. You now should have a 
sandwich with the foil in the middle, one 
edge sticking out. Lay another strip of foil 
over this whole thing, but protruding on the 
other edge. The ends of the waxed paper 
should stick out far enough that the pieces 
of foil do not touch. Roll the whole mess up 



ROLL IT UP! 





FOIL *» 2 



PAPER 



FOIL **2 



■* H*V, e- 



as tight as you can. If you do it right, you'll 
have a fairly good capacitor. It should take a 
charge up to 100 volts or so. Mine broke 
down at 150, 



. W2FEZ 



FEBRUARY 1970 



15 




Ever since that time a few months ago, when ] 
wrote, "the handle here is Ignatz. . idiot, C Garbage, 
Nuts, Alimony, Termite. Zilch. . ** :1 I have been 
swamped with unsolicited examples of this out- 
rageous phonetic claptrap. It seems that everyone 
has a favorite set of phonetics which he wishes to 
bequeath to a breathlessly wailing world* , .you 
know the type of stuff* . ."Floyd; Funny Little 
Old Yellow Don." And. . /*WA2IWS; We Are Two 
Indians With Scurvy," and all that sort of penny- 
dreadful nonsense. The more farfetched it is. the 
more unfunny it becomes. 

Now, as a chap who makes his livingTiy putting 
words together, I warrant that if 1 desired to be a 
party to these grotesquerics, I could doubtless be 
very successful at it. But I think the thing is 
starting to get out of hand. We ought, really, to 
star I clamping down on it. Unless it is a brilliant 
work of sparkling genius, I regard it as just 
sounding brass and a tinkling cymbal; and besides. 
it\ beginning to fray my nerves. 

Can you envision the result if this preposterous 
tripe is allowed to continue nourishing? Webster's 
Third New International includes over 450,0MM 
entries, each of which is fair grist for the phonetic 
fetishist's milk The possibilities are menacingly 
infinite! And, bear in mind, please, that's only one 
side of the problem; our own English language. 
How about all the others? There's Afro-Asiatic, 
Altaic, Indo-European, MaeroTChoisan. Malay o 
Polynesian, Indie. Luorawetlan, Niger-Congo, 
Sino-Tibetan, Uraiic, Azteco-Tanoan, Hokan- 

Siouan, Macro-Chibchan and Penutian a series 

of main linguistic stocks, covering some 700 
different tongi not counting regional dialects. 
Add to this the languages totally unrelated to any 
others; Basque, Andamanese. Ligurian, Yenisei- 
Ostyak. . .each of the 96 Australian aboriginal 
tongues, and all 132 o( the Papuan langi. i, and 
perhaps you'll get an inkling of the utter incon- 
gruity and hopelessness of it all. 

A long time ago I decided that the use of funny 
phonetics is pot so much a method by which io 
clarify spellings as it is a display of other things 
altogether; would-be cleverness. . .sarcasm. . .and 
most of all, ego! The wildest flights into this 



adventurism and exhibitionism arise out of a 
profoundly felt need to assert the ego. Sc h the 
surface of the guy who gives his call as Willie Broke 
I our Plate Glass Windows, and underneath you are 
likely to discover an insecure, uncertain, indecisive, 
vacillating jerk with a pronounced inferiority com- 
plex, who is attempting to bolster his inward 
weaknesses by earning a reputation for great wit 
and brilliance. 

Now please, 1 beg you. - .no more phonetics in 
the mail. I just can't take any more. However, if 
you're interested in some real clever on< I jusi 
happen to have a lew dillies. Just five bucks apiece; 
two for einht ninety-five; first come served. 

But, please keep it under your hat, I w lift want 
anyone to get the mistaken idea ego needs 

bolstering. Not a bit of it! 



There is a situation which has arisen, and Vd 
like to throw it out to see what vou all think about 

■ 

it. 

A friend of mine who was a member of ARRL 

for many years, but who dropped his membership 

just before acquiring his Extra (lass ticket, was in 

contact with another chap in the same boat. Both 

these boys are members of the highly vaunted A-l 

Operators Club, and both are well seasoned, having 

a combined total of over 65 years of hamming 

under their belts. They are not given to shoddy 

operating habits, nor have I ever found them to be 

anything but considerate and courteous. From 

any point of view they are decent people. 

Because they are not members of the League, 
they seldom read OST, and they were unaware that 
WlAW had changed its operating frequencies. This, 
despite opinions to the contrary, is neither here 
nor there. Even the membership of the League is 
not wholly aware that the frequencies have been 
changed. 

Well, anyway, these two guys were in contact 
one evening on about 38.20, In the midst of a 
transmission, and without the slightest advance 
warning, in came the Official Bulletin from 
Newington. It wiped out the QSO as effectively as 
if the band had gone dead. 



16 



73 MAGAZINE 






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Now, if Wl AW is an amateur station, operating 
within the same restrictions as the rest of us, then 
why may they be excused when they commit a 
breach of courtesy toward other stations. We are 
all expected to observe the etiquette which the 
ARRL prescribes: to check the frequency before 
transmitting, tven if a net with a scheduled 
operating time discovers that its frequency is 
occupied, the SCM has the decency to request that 
the occupant QSY so that the net may operate on 
a clear channel. If the chap who is thus asked is a 
cent le man, and most of them are. he will most 
assuredly move. But, to come right on the 
frequency without even checking to see, seems to 
me to be the most arrogant and unwarranted type 
of rule-flouting in the book. 

Since Wl AW happens to be the League amateur 
station. I feel strongly that it should be operated in 
an exemplary fashion. There is no valid excuse for 
breaking this basic regulation. In Fact, if some 
extenuating circumstance were to excuse an indivi- 
dual ham for doing this. W1AW should be operated 
so superlatively that the case would never have 
arisen. No station should break this rule. It is most 
distressing when the rule is circumvented by the 
Headquarters station. 

When the bulletin was over, the operator signed 
the call and announced that the station was 
standing by for calls. My friend gave them a call 
and they came right back to him. He took issue 
with the operator, asking him why he had not 



checked the frequency before transmitting the text 
of the bulletin. The operator replied, "I can't 
comment about that. If you wish to complain, you 
may write to the League, and take it up with 
them." 

Well, that's it. What do you feel about it? Do 
you think that W1AW, despite its undeniable help 
to amateurs, should have the right to ignore the 
good operating practices which we are all con- 
stantly enjoined to observe? I do not think so, But 

that's only my opinion. What's yours? 

* * * 

This isn't an original idea, of course, . - Tm 
sure somebody must have proposed it. Why, if 
there's a thing called Operator of the Month, isn't 
it feasible to publish a list called Lid of the Month? 
Some of the characters on the ham bands reallv do 
deserve this sort of publicity, as you will un- 
doubtedly agree. It's just too bad that the most 
iniquitous ones invariably operate anonymously, so 

that it's difficult to identify them. 

One thing is certain. If you would like to 
discourage the intrusions of unwelcome carrier 
throwers, burperv whistlers, n//ers. and other 
intruders, never. . . .but never, never comment 
openly about them. That's exactly what they wjnt 
in the first place. So don't give them the satis- 
faction of successfully provoking you into an 
altercation on the air. If you ignore them, chances 
are thai they will move off your frequency and 
seek someone else who might just rise to the bait. 



FEBRUARY 1970 



17 



^^ 



— 



I 

Apropos ot my recent rhymed diatribe against 
TV commercials, I recall with delicious amusement 
an incident of about six years ago. 

My father, who had a marvelous admixture of 
bored cynicism and a highly sophisticated sense of 
humor, loathed and abominated TV commercials. 
One of these in particular used to offend him very 
much, There was an animated character with a 
head formed of a seltzer tablet. He .sang a childish 
little jingle which ended with an advertising slogan 
for the product. You simply could not avoid this 
thing . . M was like the plague; repetitious and 
redundant. 

Dad got hold of an old mezzo-tint of Socrates. 
drinking the cup of hemlock. In bold letters, and 
with a red marking pen, lie inscribed it, and sent it 
to the advertising agency which handled the 
account. His inscription read, simply, "RI LIfl IS 
JUST A SWALLOW AWAY/ 1 

Vd like to discuss an event which rankles in the 
breast of almost every amateur even now, several 
years afterward. I refer, of course* to the removal 
of 27 MHz from the amateur spectrum, and its 
reassignment and deterioration into the monstros- 
ity and misbegotten mishmash it was inevitably to 
become. 

Most of us have to lake a position. We cannot 
blow hot and cold with the same breath. We 
annot plant both feet firmly in mid-air, Yet, there 
arc those who pretend to be the champions of both 
contending forces, both unalterably in opposition 
to each other. , . ,both of whose interests He clearly 
in diametrically opposite directions, 

Can you imagine a man playing both sides of a 
chessboard? Can you conceive of one general 
acting as strategist for two warring armies? Can 
you picture one attorney representing both plain- 
tiff and defendant in a lawsuit? And, if such a 
law \ er were to advise you to act in such and such a 
manner, would you be expected to follow his 
advocacy with implicit faith and confidence? I 
think not. You would be most imprudent, if you 
did, 

A certain publishing compatn issues two maga- 
zines; one for hams: the other for CB'ers. Now this, 
in and of itself, is certainly no sin. It is perfectly 
possible to serve the interests of both, SO LONG 
AS THEY DO NOT ATTEMPT TO GAIN AN 
ADVANTAGE I OR ONE. AT THE EXPENSE 01- 
THE OTHER. Through the years, however, in the 
pages of CO Magazine, we have seen hints, outlines, 
draughts, suggestions, proposals, resolutions, and 
motions, all calling for the creation of additional 
frequencies for Citizens 1 Band. They have called 
for the implementation of a new class of amateur 
license which would open up the ham ranks to 
ClTers, (as if the doors were closed to them now). 
There is a persistent subterfuge-a nice little 
fiction -that these people constitute a pool of 
potential amateur operators, the encouragement of 
whom all will ultimately supplement our growth, 
and make us strong and healthy, In other words, . 
**LeCs have this teentsy-weentsy slice of 10 



meters, fellows. You're not using it anyway, Let\ 
allow r these nice, deserving folks to use it so that 
they can develop their skill and talent. They are 
really different than you think, way down deep 
inside. They are serious, earnest, purposeful and 
dedicated, and we owe them an opportunity to 
develop these splendid and sterling qualities so that 
they may take their rightful place beside us as 
full-fledged amateurs. 

Now, really, 1 ask in all candor. . .is there a 
single ham who has the slightest inclination to take 
this stuff seriously? I certainly hope not! The only 
quarter in which it might meet with approval is 
among the CB manufacturers. 

Picture this fantasy. The moment these fine, 
misunderstood fellows are given these additional 
frequencies, they will instantly begin to observe all 
the ICC regulations. By some strange and mira- 
culous atavism, they will become first-class opera- 
tors. The only thing, you see, that keeps them 
from doing this right this very minute, is because 
the poor dears are all squeezed and squished into 
those horrid, little 23 channels. That's why they 
call skip, use VFOs, run high power, use illegal 
antennas, don't give proper callsigns, interfere 
intentionally . persist in the use of profanity and 
obscenity, and break all the other rules. But never 
you mind; the moment they are granted this 
allocation, they will change. They will become 
fine, law-abiding members of the ham fraternity, 
and dedicate themselves to constructive purposes. 
They will be a credit to us all. Just do away with 
the nasty old code and theory requirements. . . 
please . , .pretty please . . .and you'll be surprised 
at how they'll change* 

Tm not anxious to pillory CQ. 1 have some very 
good friends there people for whom 1 have the 
utmost regard. But I can't help feeling that the 
front office allowed its "druthers" to he seen in 
public print, in spite of -not because of- these nice 
people. And I think that we hams ought to express 
our united opposition to all such plans, though 
they may sound ever so lofty and constructive. 
They can have but one result. . .the weakening of 
amateur radio. And there has never been a time in 
our history when we needed so badly to maintain 
all the strength we can muster, 

* * * 

A few weeks ago it was decided that I would he 
"doggo" on the subject of the League for a while. 
Wayne felt, and I agreed with him, that there would 
be no point in continuing to take issue with certain 
aspects, since I had already expressed most of the 
reasons for my objections, and had given voice to 
many of the sentiments unexpressed by the com- 
mon, garden-type variety of ham, which deserved to 
be articulated. I fully intended to concern myself 
with other matters which would be of interest to the 
readership. But I find that I cannot seem to get away 
from these issues, after all. The latest issue of QST 
includes a League proposal, which, if advanced to 
FCC as it is now proposed, can possibly be even more 
dangerous than any other ARRL*sponsored change 
within memory, including incentive licensing. 



18 



73 MAGAZINE 







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At this point, allow me to emphasize unequivo- 
cally that I have absolutely no prejudice against 
those who hold Technician grade licenses. If I do 
object to any of them, it is on the ground that some 
of them operate in violation of the spirit, if not the 
letter of the FCC regulations. Many of them, prob- 
ably a majority, conduct themselves conscien- 
tiously, but it is simply impossible to ignore the 
infantile antics of the violators among them. This is 
not to say that there are no culprits among other 
classes of amateurs. But the reasons are not the same. 
In my judgment, one of the important reasons for 
the misbehavior of certain individuals among Techs, 
is that they obtained their licenses fraudulently to 
begin with. Many well-meaning operators, acting in 
the prescribed role of volunteer examiners, and 
probably in a spirit of overpermissiveness, have given 
an inordinate measure of assistance to applicants foT 
the Tech ticket. In some cases the CW requirements 
were completely bypassed. In other cases the exami- 
ner rendered illegal aid on the written portions of the 
examinations. In this fashion a group of persons who 
were never really interested in conforming to the 
stated purpose of this particular grade of license, but 
who were merely desirous of pursuing the communi- 
cations end of the hobby, were permitted to infil- 
trate the ranks of the Technicians. They became 
figuratively and literally marooned in that category, 
because there were but few avenues through which 
they might upgrade their skills in order to meet the 
standard requirements for the other grades. There 

have been Techs, of course, who buckled down to 
work, and developed their code speed. But, on the 
whole, they did not seem to care too much about 
becoming General class operators, being content, 
rather, with staying in their own special niche. 

There is no point beating about the bush. You 
have heard, as I have, the expression k *maii-order 
license"' used over and over again. There is no doubt 
that a sizable segment of those who hold this ticket 
earned it as a result of less than fastidious observance 
of the rules by the volunteer examiners. And this 
practice, though it might appear to be negligible in 
actual numbers, has tended to lower standards for 
entire group. 

Now ARRL has decided to propose that Techs be 
permitted phone and other privileges between 29.5 
and 29.7 MHz. There is no mention of any qualifying 
examination for this additional privilege. And I be- 
lieve that each and every ham who had to go and 
upgrade his ticket in order to continue to operate, 
not on newly granted frequencies, but on the same 
frequencies where he had previously been entitled to 
do so, should be raising his or her voice in protest. It 
may be perfectly true that this particular slice of the 
spectrum is not overused. It may be lying completely 
fallow. But this fact should not constitute justi- 
fication for cheapening or vulgarizing it in this fash- 
ion. 

I say, compel all Technicians who wish to avail 
themselves of this or any additional privilege to 
submit to a proper examination in the presence of an 
official FCC examiner. Those Techs who wish to get 
this additional slice of the spectrum should be, and 
undoubtedly will be, in my view, willing to buckle 



20 



73 MAGAZINE 




down, as did the rest of us in similar circumstances. 
This privilege, if offered at all, should not be a free 
gift, but an incentive. If the League truly believes 
that incentives will really upgrade the quality of 
amateur operations, then it must not allow this 
concept to be torpedoed with an inconsistent ap- 
proach toward one segment of the ham population! 
If the League is thinking that it will gain membership 
;js a result of a huge and enthusiastic influx of 
grateful Techs, responding to this magnanimous ges- 
ture on the part of Newington, let them contemplate 
the wholesale hegira from the ranks by thousands of 
members, already disenchanged with the way things 
have been going. For every grateful Tech who joins 
ARRL, I believe there will be a score of members of 
long standing who will simply quit in disgust. 

I am very unhappy with this proposal I would be 
much more unhappy if I thought that my fellow 
amateurs would allow this proposal to go through 
without a mighty outcry of dissent. If we do not 
yammer to our directors and to the League execu- 
tives about this injustice, we will not have the right 
to complain about it afterward! Nor would we de- 
serve that right* 

Here is a golden opportunity for us to test the 
League's willingness to be responsive to the desires 
and needs of its members. Typically; of course, in its 
time-hallowed attitude of paternalism, the League 
will tell us that it knows what is best for us. Is there 
anyone left who actually believes this? Is there any 
soul who has observed the debacle of the unused 
sub-bands, and the horrendous congestion in the 
unrestricted portions, who can be gullible enough to 
buy this ancient and worn-out canard? 

I would be very much surprised if this atrocious 
proposal should meet with the approval of the 
majority of the amateurs. Since it would result in 
an advantage to some, gained through preferential 
bias for this one license grade, it spells a disad- 
vantage, in effect, for all the rest of us. 

Let us all make certain that we express our 
feelings on the question. Let no amateur fail to 
communicate with ARRL and its leaders, so that 
we may avoid a perilous situation in future years. 
This proposal constitutes a dangerous precedent. It 
would enable some FCC, as yet unnamed, perhaps, 
to reassign portions of our bands to whomever it 
wishes, on the simple ground that it is right to 
exact standards of ability from some, while permit- 
ting others to ignore any standards whatsoever! It 
would also establish that frequencies which are not 
widely utilized may be preempted by groups which 
might make more use of them. On this basis it 
would be possible to witness a gradual attrition of 
the entire amateur spectrum, through their reas- 
signment to anyone or any group with sufficient 
influence to convince or mislead the Commission, 

Please, I entreat you with all earnestness and 
sincerity, do not let this proposal get to first base. 
This could be the most important decision you can 
make during your entire amateur life* Don't let it 
get through, especially by default. Write, wire, and 
call your director. Do it today!!!! 

. . . Dave Mann K2AGZ* 




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Emergency Net 
Changes Name, Frequency 

ME DINET — Medical Information Network- 
is the new name of the Public Health 
Service Emergency Radio Network, the Secretary 
Of Health, Education, and Welfare announced 
today. The network was organized a year ago by 
the Division of Emergency Health Services, Health 
Services and Mental Health Administration, to 
provide communication during health emergencies 
when downed telephone lines have closed normal 
communication channels. 

MEOINET is made up of employees of the 
Department of Health, Education, and Welfare 
(HEW) who live outside the Washington, D.C. 
metropolitan area and who are licensed amateur 
radio operators, or "hams." MEDINET's most vital 
function is to provide rapid communication among 
health officials at the local, state and federal levels 
during disasters, When normal communications 
channels are closed, MEDINET steps in to insure 
the fastest possible response to the health needs of 
disaster areas. Participation in MEDINET is volun- 
tary. It is undertaken as a public service by the 
HEW employees involved. When an emergency 
occurs, MEDINET members are excused from their 
normal duties so that they can participate in the 
network. Network control for MEDINET is pro- 
vided by the National Institutes of Health Radio 
Amateur Club station, K3YGG, at Bethesda, 
Maryland, a Washington, D.C, suburb. 

The change of name, from PHS Emergency 
Radio Network to MEDINET, will permit routine 
on-the-air meetings of the network's members 
without any Federal connotation. To promote the 
use of a single frequency by all medically oriented 
networks— such as the Medical Amateur Radio 
Council, Ltd., an organization of physician hams— 
ME Dl NET's frequencies were recently changed to 
7260 kH2 and 142S0 kHz (with 21360 kHz as an 
alternate). 

Presently, MEDINET is meeting on the air every 
Monday at 12:00 noon and every Wednesday at 
5:00 p.m. Eastern Time- MEDINET Control, 
K3YGG, operates at 20 meters on 14280 kHz and 
40 meters on 7260 kHz simultaneously at these 
times. 

A few of the MEDINET members do not have 
transmitters powerful enough to communicate 
directly with Washington, D,C. MEDINET, how- 
ever, is set up so that it can relay messages from 
station to station across the continent. This tech 
nique was used with dramatic success in the recent 
Hurricane CamiJle disaster on the Gulf coast. 



Announcement 

12th Annual Dinner 

The East Coast VHF Society's 12th annual 
dinner will be held Saturday, March 21, 1970, at 
the Neptune Inn, Route 4, Paramus, N.J., starting 
at 7 p.m, Ted Mathewson W4FJ will talk on 
'VHF— Past, Present, and Future/ 1 Awards will be 
given by Ed Tilton W1HDG, including awards for 
highest single and multioperator station in the 
September VHF contest. The menu will be prime 
ribs of beef and tickets will be sold for $7.50, 
Group reservations are available in blocks of 5 to 
10. Ticket deadline is Wednesday, March 11. For 
tickets and reservations write the East Coast VHF 
Society (WA2WEB), PO Box 1263, Paterson NJ 
07509. 



Amateur Rad io 

AMATEUR RADIO IN INDIA 

Marie Welsh W6JEP 
Reprinted from LERC Bulletin 

G- V. Sufu (VU2GV) was kind enough to send a 
copy of the Radio & Electronics Society of India 
(RESI) Book Series 1 Amateur Radio Regulations 
in India, compiled by M. V. Kini (VU2SZ), This 
1968 First Edition is very interesting and our 
readers may appreciate the following highlights 
which I've extracted from the book: 

1. No 160 or 6 meter privileges. 

2. 10 kHz only on 80 meters; 3890 3900 kHz. 

3. 100 kHz only on 40 meters; 7,0-7.1 MHz. 

4. 20, 15, and 10 meters are the same as our 
bands. 

5. 2 meter band is 144-146 MHz, 

6. 420-450 MHz also used by radio altimeters, 

7. 1215 1300 MHz shared with fixed and 
mobile services, 

8. 2300-2450 MHz primarily assigned to fixed, 
mobile, and radio location services. 2450 
MHz shared with Industry, Medicine, and 
Scientific groups, 

9. 3300-3500 MHz shared with fixed and 
mobile services, 

10. 5650 5850 MHz shared with fixed and 
mobile services; 5800 MHz is for industry, 
medical, and scientific purposes. 

11. 10,000-10.500 GHz and 21-22 GHz are used 
as ham bands. 

12. The top license is called Grade L This ticket 
is available to those who are 16 or older. 
The code test is at 12 wpm and the theory 
test is about the same as our Novice exam. 

13. The other license is called Grade II. This 
ticket is available to those 14 or older. The 
code test is at 5 wpm and the theory test is 
25% easier than the Grade I exam, 

14. The maximum input power for SSB oper- 
ation has been increased from 100 to 400W 
PEP. 

15. Mobile operation is now authorized on the 
VHF bands, 

16. There are about 500 licensed hams in India, 
and the majority of them are quite new to 
the hobby. 

17. Ham literature is very scarce in India and 
ordinary electronic components are Just 
about nonexistent, 

18. Amateur licensing exams are conducted (by 
appointment only) at 5 monitoring stations 
of the Department of Communications and 
Civil Aviation with requests addressed to the 
Wireless Adviser, Wireless Planning and 
Coordination, Ministry of Transport and 
Communication, 

19. The Grade I exam fee is 10 rupees and the 
Grade II fee is 5 rupees. 

20. Grade I station applications cost 15 rupees 
and Grade II ones cost 10 rupees. 

21. Grade I licenses will soon be renewable for 3 
years at 42 rupees. 

22. Grade II licenses are not renewable after 3 
years; the holder must upgrade to Grade I or 
lose his license, 

23. Ham licenses can be granted to nationals of 
other countries, 

24. Station particulars must be detailed on the 



22 



73 MAGAZINE 




News Page 

Station application. If not commercial or 
surplus equipment, a diagram of the trans- 
mitter must be attached. Receiver details 
must be attached. A sketch of the antenna 
(showing dimensions and mechanical sup- 
ports) must be included, 

25, The powers at the (1) power supply, (2> 
final amplifier input, and antenna input 
must be stated on the station application, 

26. The desired transmitting and receiving fre- 
quencies must be stated on the station 
application. 

27 f The equipment frequency range capability 
must be stated on the station application, 

28, Two passport-size photographs are required 
with the operator application. 

29, The applicant's physical description and per- 
sonal data are required on the operator's 
application. 



FCC Notes 

CB Traffic Reporting Authorized 

CB rules (Section 95.83(a) (14) have been 
amended to permit licensees to transmit informa- 
tion on highway conditions to persons or emer- 
gency organizations furnishing such information to 
the motoring public by way of radio broadcast 
facilities (Docket 18625; RM-1388). The amend- 
ment will provide for road information furnished 
by a CB radio station to be compiled and edited by 
the broadcaster and then announced over a broad- 
cast facility. 

40 Meter Segment Opens 
for Ham Band Marine Operation 

Amendment of the amateur service rules Section 
97, 95(b) (2) concerning maritime mobile operation 
permits United States amateurs, when outside the 
jurisdiction of a foreign government, to operate in 
the 7.0-7.1 MHz band in areas of Europe, Africa, 
and Northern Asia (Region 1) and Southern Asia 
and Oceania (Region 3), effective December 31, 
1969. The 40 meter frequencies from 7 to 7.1 MHz 
have been allocated for exclusive use of the 
amateur radio service on a worldwide basis. 



Fort Sill Fest 

The annual Fort Sill hamfest will take 
place in Lawton, Oklahoma on February 22, For 
details, write Lawton— Fort Sill ARC, Box 892; 
Law ton OK 73501. 



Storm Warning 



In the March 1969 issue of Popular Science 
there was an interesting article explaining the 
Newton WeNer system of using your TV set as a 
tornado warning device. The mechanics are simple: 

• Tune your TV set to channel 13 

• Turn the brightness control until the screen is 
dark 

•Tune to channel 2 

If the screen is white, then there is a tornado 
nearby. White streaks on the screen are an indica- 
tion of lightning activity. A dark screen shows there 
are no electrical storms in the area, Jf there is a 
local station on channel 2, you may see its picture 
instead of a blank screen. 

Newton Welter found that tornados have an 
oscillating electrical field around the eye. The 
frequency of this oscillating field is very close to 
55 MHz (that is, channel 2). One darkens the 
screen while tuned to channel 13 to give a 
reference as far from 55 MHz as possible. The high 
signal level produced by the tornado or electrical 
storm is enough to turn the screen white on 
channel 2. 

. . . WA6YZD, as lifted from 
the Sacramento Club paper 



Blossomland Annual Auction 

The 3rd Annual Blossomland Amateur Radio 
Auction will be held March 15, 1970 at the Youth 
Memorial Building, Berrien County Fairgrounds, 
one mile north-west of Berrien Springs, Michigan, 

Last year over 300 amateurs turned out for 
Southwestern Michigan's fastest growing ham 
event, and went home with carloads of fine gear 
{or money). The 1970 auction promises to be 
bigger and better. 

Acres of free parking will be available for the 
trailerloads of bargains that will no doubt show up. 
Don't pack a lunch. . .hot food will be available. 
Prefer to do your own selling? Rent one of the 
swap tables. If that fails, a skilled auctioneer will 
put your gear on the block. 

One happy ham went away with a Heathkit 
Hotwater 100— the grand prize last year. A lot of 
others won smaller items. What wilJ this year's 
door prizes be? Be there March 15 and find out. 

Coming from out of town? Just get on US 
31-33 to the Fairgrounds north of Berrien Springs, 
Running mobile on 75 or 2? Direction service and 
call-in on 3925 or 146.94 FM, 

Check your shack now. ♦ .and be at the auction 
between 10 a.m, and 1 p,m, (starting time) to 
convert that old gear into something easier to 
carry, . , money. 




OLD TIMERS 



The "Old Timers Dinner" for the Southeast 
LLS. sponsored by the Birmingham Amateur Radio 
Club will be held at 7:30 p.m,, February 14, at the 
Holiday Inn East (Highway 7B East). Leland 
Smith, W4AGI/W5KL, will be the featured speak- 
er. 

This appears to be an annual event, predicated on 
the tremendous crowd attending last year, A 
license issued before 1930 entitles a ham and his 
wife to a free dinner. 

Antique equipment, magazines and "hams'* will 
be on display. 

For further information contact W4GET or 
W4AXL, Box 603, Birmingham AU 



FEBRUARY 1970 



23 



■ 




24 



73 MAGAZINE 



II 






, 




The circuit boards were hand painted 
with photoresist after first ruling the edges 
of the lines with a resist pen. Then the 
circuit boards were etched with ferric chlo- 
ride. The ends of the straight dipole section 
were plugged, and the coils held in place 
with a single screw in each end. There is one 
left-hand and one right-hand coil, so that 
with the conducting sides of the coils turned 
toward each other* the currents in the coils 
oppose each other to reduce premature 
radiation. 

The final touch is the tuning means, 
which consists of telescoping brass tubings 
(I obtained them from a local hobby shop). 
The inner tubing is 1/16 in. O.D. and the 
outer tubings are soldered to the ends of 
their respective coils. 

This little antenna turned out to be my 



favorite, as it was inconspicuous and could 

be taken down and lost in a small piece of 
airplane luggage. Since it is matched to a 50 
ohm coaxial cable (usually RG-58/U), all 
that is necessary is to connect it, tune it, and 
go on the air. 

Good results were obtained from the 
outset with the antenna sitting on the 
nylon web of a lawn chair on the balcony. 
In the fall I hung it in two plastic waste- 
baskets, one inverted on top of the other; 
there it sat all winter long bringing in the 
contacts. The maximum power used was 
provided by four 1625 lubes in a homebrew 
grounded-grid linear. Estimated input is 
300W PEP with additional feedthrough 
from the exciter. That power level is about 
the limit for the printed circuit coils. 

These antennas have been a real fun 
thing, from the very first successful model — 
which was a 2 ft dipole on 40 meters. A 
prototype 4 ft antenna was made for 40 
meters and a few were made and sold to test 
the market. There is presently no commer- 
cial product available, but a patent* has 
been granted on the antenna. 

The antenna system comprises an end- 
loaded dipole with matching impedance in 
the center. The straight dipole has a high 
radiating efficiency, and there is undoubted- 
ly a substantial contribution from the strong 
electrical dipole produced by the two end 
coils which are opposed magnetically. This 
accomplishes two things; 

1. Radiation at right angles to the prin- 
cipal field of the straight dipole is reduced 
or nearly eliminated. 

2, Radiation off the ends is also greatly 
reduced, thus avoiding or reducing losses 
which might otherwise occur through cou- 
pling with nearby lossy objects. 

Although a highly efficient antenna 
should be possible in this configuration, the 
efforts have been concentrated on making 
small lightweight antennas, for economy, 
ease of handling, and with minimum space 
requirements. The actual efficiencies would 
be very difficult to calculate since the 
distribution of the current in the coils is a 

*Patent No, 3,432,858 owned by the author. The 
author does not object to having amateurs build 
these antennas exclusively for their own experi- 
mental use* 



FEBRUARY 1970 



25 





The keycase and ruler are shown beside the 18 in. 

15 meter dipoJe for size comparison, A string 
attached to a clamp under the screw on one end 
permits hanging the antenna from a convenient 
support. One word of caution: the coax must he 
kept several inches away from the coil edges to 
avoid a detuning effect 

complex phenomenon- However, with an- 
tennas, performance is the prime criterion— 
and this has proved very gratifying; the 
antennas have been tested and used by 
several of the author's friends with consis- 
tently good results. 

One of the greatest advantages of the 
antenna is its small size and weight which 
permit it to be placed more favorably at 
times than such antennas as the ground - 
based vertical or a half-wave dipole. Taking 
advantage of its size and independence from 
the ground, it can be placed at an optimum 
height for the desired angle of radiation. Or 
it can be used either horizontally or vertical- 
ly to achieve optimum propagation over 
short or long hauls. For example, the 4 ft 40 
meter dipole worked very well vertically for 
the long hauls, but better horizontally for 
distances of 60 to 100 miles. 



The advantage of raising the antenna to 
an optimum height, which for longer skips 
may be one-half to one wavelength above 
the ground, may be seen from the graphs 
contained in an article by W, H. Anderson 
VE3AAZ (Antenna Behavior Over Real 
Earth, QST, June 1965, pages 61-64), The 9 
ft 40 meter antenna weighed 3 1/2 pounds 
and thus could be placed on a light support 
anywhere on the house or other structure 
where a little free space was available. Thus 
in a vertical position at some height above 
the ground, it might perform as well, or 
better, than a quarter-wave ground-based 
vertical. As seen from the above, there is no 
reason why the antenna cannot be mounted 
horizontally and rotated. This, of course, has 
been done, and although the tests made were 
not extensive, it was found that the short 
dipole (4 ft on 40 and 8 ft on 80 meters 
have been tried this way) behaved direc- 
tionally about like a half-wave dipole. 

Very good results have been achieved 
with the 40 meter dipole in the vertical 
position at a height of 25 ft, Africa and 
Ireland were worked from the W9 location 
with this arrangement. However, one thing 



26 



73 MAGAZINE 






was learned with the 40 meter antenna on 
the top of a telescoping steel pole. The base 
of the pole was on the ground, and when 
the ground was wet and the pole extended 
to a quarter-wavelength, the pole started reso- 
nating and changed the radiating resistance of 
the short dipole and § consequently, the vswr 
which is normally kept low (1:1 at the 
center-tuned frequency in the vertical posi- 
tion when optimum adjustment is achieved). 

The experience with the radiating sup- 
port, of course, is indicative of what can 
happen with any portable antenna. It is 
subject to variations in characteristics when 
brought near other objects with nearly the 
same frequency of resonance. When the 
lower end of the telescoping steel pole was 
insulated from the ground, it was possible to 
extend it to any height (within its 40 ft 
capacity) without changing the tuning of 
the antenna. Of course, this was with the 
antenna in the vertical position. With the 
short dipole in the horizontal position, it 
could be expected to change its character- 
istics as its height was changed due to 
imaging in the ground. 

The possibilities of experimenting with 
antenna height vs propagation effects on the 
40 and 80 meter bands with small light- 
weight antennas of this type are excellent 
since they require only lightweight supports 
and may be easily mounted in either the 
horizontal or vertical positions down to a 
very small fraction of a wavelength from the 
ground. The 40 meter dipole worked very 
well 6 ft above the ground and could 
undoubtedly be used even lower. This was 
in the vertical position which, with a half- 
wave dipole, would put the current node 40 
ft off the ground (instead of 8 ft ). In the 
horizontal mode, both the 4 ft antennas on 
40 meters and the 8 ft antenna on 80 
meters have been mounted directly to a 
steel mast with right-angle clamps with good 
results. The clamps were placed close to the 
center of the straight dipole section and on 
the same side to which the coax shield was 
connected. 

One of the first questions asked is 
whether multiband operation is possible 
with these short dipole antennas. First, the 
antennas may be tuned to the odd har- 
monics of the fundamental frequency of the 



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FEBRUARY 1970 



27 




antenna. Thus, the 4 ft dipole for 40 meters 
worked very well on 15 meters. One 2 ft 
dipole for 15 meters and 20 meters tuned to 
a low vswr on 6 meters* 

The 2 ft dipole for 15 and 20 meters 
contained a trap in each coil to permit 
operation on the two bands, Fine adjust- 
ment in both bands was accomplished by 
adjusting taps on the inside turns of the end 
loading coils. The coils tune sharply, much 
like mobile antennas, as the radiating resis- 
tance is low and the overall Q of the 
antenna is high. It was found that with the 
18 in. dipole for 1 5 meters^ the entire phone 
band could be tuned with my SBE Model 34 
transceiver. However, the 4 ft dipole re- 
quired adjustment to cover the entire phone 
band on 40 meters, as when tuned 1:1 at 
the center of the phone band, the vswr at 

7.2 and 7.3 MHz was about 3:1. An 
experimental remote tuning device with a 
reversible motor was built and operated on 
40 meters. This device permitted tuning 
right "on the button" on both 40 and 15 
meters. 




The co it dimensions for IS meters are 7-3/8 by 
7-3/4 in» t and the turns are purposely made wider 
in the center where the current is higher. The inner 
conductor (first turn) is 1/4 in. wide t and the next 
two graduations in conductor width are supposed 
to be 3/16 and 1/8 in. respectively. On the left side 
may be seen the tuning stub f which is a 1/16 in. 
O.D. brass tube which slides in a larger tubing. The 
larger diameter tubing is soldered to the end of the 
printed circuit coil 

Three 4 ft dipoles were wide-spaced 6 ft 
above the ground to form a beam. As they 
were fixed and could not be rotated, the 

direction of the beam was changed by 



running out and quickly interchanging the 
director and reflector or front and back 
dipoles. The beam seemed to have a good 
front-to-back ratio, but the gain was not 
checked. It appears that two or three such 
dipoles on a boom might be great for 40 or 
80 meters. They could be used as a rotatable 
beam either with horizontal or vertical 
polarization. This could be changed remote- 
ly by a motor drive, which should lead to 

some interesting experiments in propagation 
effects. 

Tuning these antennas requires some 
type of instrumentation to determine opti- 
mum operating conditions. The minimum 
should include at least a vswr meter. The 
antennas should be tuned so that near zero 
or very low reflected power is in evidence. If 
the center matching impedance is proper, 
the only tuning required is to adjust the two 
coils until the antenna is resonant at the 
operating frequency. Then the vswr should 
be near 1:1. Initially, if the matching 
impedance is a little off, it may not be 
possible to bring the reflected power down 
near zero, but a low point will be found 
indicating resonance has been achieved. In- 
creasing or decreasing the matching imped- 
ance should then permit achieving a low 
vswr. Retuning the coils may be necessary 
if a large change is made in the center 
matching impedance. 

A grid dip meter or other instrument 
such as the Omega-t Systems antenna noise 
bridge can come in handy to find out the 
resonant frequency of the antenna before 
tuning. The antennas are generally made with 
slightly longer coils than necessary to permit 
adjustment to various conditions. The 18 in. 
dipole for 15 meters has a jumper from the 
center conductor to the first turn to bring 
the antenna into tuning range. The jumper is 
a piece of bare copper wire soldered at the 
ends. 

For the amateur who likes to experi- 
ment, or the amateur with limited space for 
antennas, these antennas have many inter- 
esting possibilities. For the amateur who has 
everything, one for portable use, or maybe 
for use just for the fun of shocking someone 
by saying, "I'm using a 4 ft dipole antenna 
on 40 meters," may be the order of the 
day. . . . K9LGH" 



28 



73 MAGAZINE 













MODEL 508 VFO — SWAN 500C TRANSCEIVER — 117XC POWER SUPPLY— MARK II LINEAR 

For several years Swan Electronics has been specializing in value engineering of single sideband 
transceivers to give radio amateurs the best possible equipment at the lowest possible price. We're 
pleased to say that we have thousands of satisfied customers all over the world, many who have 
purchased their third or fourth Swan as we continue the evolutionary improvement of our product. 
(Trade-in value of a used Swan is well above average.) We would like to say that the station illus- 
trated above is a typical Swan station, but that would be misleading. Actually, the average Swan 
owner finds the quarter kilowatt or half kilowatt transceiver very adequate for his operating needs. 
What the picture illustrates is some of the Swan accessories that will add more versatility and 
greater operating pleasure to your Swan station. For the DX operator, the model 508 external VFO 
provides separate control of transmit and receive frequencies, or for the MARS and Net operator, 
the 510X crystal oscillator provides up to 10 fixed channels. For breaking through those weekend 
QRM pile-ups there's no better cure, egally, than the Mark II Linear Amplifier with its 2000 watts 
of P.E.P. 



© TOP OF THE SWAN-LINE 

THE FAMOUS 500C TRANSCEIVER 

520 watts P.E.P. input on 10, 15, 20, 40 and 80 meters. 
Finest crystal lattice filter with 1.7 shape factor. Vz 
microvolt receiver sensitivity. Voice quality, perform- 
ance and reliability are in the Swan tradition of being 
second to none. $565 

© MODEL 508 
EXTERNAL VFO 

Provides full coverage of 80, 40, 20, 15 and 10 meters 
in 8 ranges of 500KC each. Enables you to transmit 
and receive on separate frequencies. Plugs directly 
into either the 50OC or 270. $145 

© CRYSTAL CONTROLLED 
MARS OSCILLATOR 

For Mars or Net operation. Model 510X. 10 channels. 
Plugs directly into 500C or 270. Less crystals. $55 

© POWERHOUSE MARK II LINEAR AMPLIFIER 

2000 watts, P.E.P. input, 10 through 80 meters. Uses 
two 3-500Z triodes. Complete with matching power 

supply. $660 

© MODEL 11 7XC 

MATCHING AC SUPPLY FOR 500C TRANSCEIVER 

For 117 volts, 50-60 cycles, with speaker and phone 
jack. $105 



© 12 VOLT DC POWER 

SUPPLY FOR 500C TRANSCEIVER 

Model 14-117, designed for mounting under hood. In- 
cludes cables, plugs and fuses. Can operate from 117 
volt AC by detaching DC module and plugging in 117 
volt line cord. $130 

SWAN HORNET 
BEAM ANTENNAS 

Latest addition to the Swan-Line. High quality, high per- 
formance antennas for the amateur bands. Best known 
are the famous Hornet Tribanders, made in 2, 3 and 4 
element models. The TB-1000 series is rated at 2000 
watts, the slightly smaller TB-750 at 1500 watts. 

TB-1 000-4 4 element $159 



TB-1000- 3 3 element 
TB 750-2 2 element 
TB-750-3 3 element 



■ * 1 <■ 



129 

89 

109 





ELECTRONICS 

OCEANSIDE, CALIFORNIA 
A Subsidiary of Cubic Corporation 



" 




HIGH PERFORMANCE 

CONVERTER 

B 








Alan Wilson WA9HES 
308 East Wood Street 
Hillsboro !L 



Been looking around frantically for one of the good old 
converter circuits? Here's one thai uses a Nuvislor for high 
gain and low noise on 6 meters. 



The first addition lo my 6 meter station 
was the converter described below. The 
unit is designed with the idea of obtaining 
high performance with a minimum of cir- 
cuitry. 1 will attempt to describe the unit in 
such a way that it can be easily duplicated. 

Circuit 

A 6CW4 Nuvistor serves as the rf ampli- 
fier. Oscillator and mixer functions are 
provided by a single 6U8A, The 6CW4 must 
be neutralized, but the low noise figure 



obtained by the use of this tube makes the 
extra effort worthwhile. The pentode section 
of the 6 USA is utilized as the mixer. This 
arrangement provides adequate output for 
any reasonably sensitive receiver. 

The oscillator uses the triode section of 
the 6U8A, A third overtone crystal deter- 
mines the frequency. In my unit a 43.2 MHz 
crystal gives coverage from 50.2 to 50,5 
MHz using the 40 meter band as an i-f. Other 
crystal frequencies could be used to cover 
other segments of the band, or if a general 



30 



73 MAGAZINE 






coverage receiver were employed, a 43.0 
MHz crystal would cover the entire band 

with output between 7 and 1 i MHz. 

Construction 

In order to obtain optimum results the 
converter should be built in accordance with 
good VHF practices. All components should 
be mounted rigidly, keeping the leads as 
short as possible. Prewound Miller coils are 
used throughout- Note that the mixer out- 
put coil is from the 21A00ORBI series. A 
coil of the same inductance but from the 
smaller 20A000RBI series would not allow 
for winding the output link. I used silver 
mica capacitors for all tuned circuit and 

coupling purposes. Small tubular ceramics 
would serve as well. All bypassing is done 
with 1000 pF ceramic discs. 

The only critical part of the converter is 
the neutralization circuit. The 1.5-7 pF 
neutralizing capacitor must be secured solid- 
ly. The body of the 6.8 kil resistor should 
be positioned as close to the lower end of 
L3 as possible. This is necessary because the 
resistor has a dual purpose, It functions not 
only as a series dropping resistor but also 
serves to keep the bottom of L3 above 
ground. 

Tuneup Procedure 

The first step after applying power is to 
adjust L7 for maximum rf output as indica- 
ted by a grid dip meter in the wavemeter 




The rf stage with the associated neutralizing cir- 
cuitry is at the upper left. Output from the mixer 
is coupled to J2 via a length of RG-58/U. 

position. Next, connect a short length of wire 
to Jl and set the grid dip meter to generate a 
6 meter signal. Now connect the converter 
to the receiver with a short piece of coax 
and adjust L5 for maximum signal as indi- 
cated on the receiver's S-meter. Next, set the 
neutralizing capacitor at midrange and tune 

L2, L3 f and L4 for maximum signal 
strength. Now disconnect the 6.8 k£2 resistor 
from the high voltage source and adjust the 
neutralizing trimmer for minimum signal as 
noted on the S-meter, Finally, reconnect the 
resistor and repeak all five coils. The con- 
verter is now set for near optimum perfor- 
mance. 




43 2 VHf 

X 

Fig, J, Cn is a ceramic trimmer \ CI is a 2,5 pF 
'gimmick' made by twisting two pieces of 22 
AWG hookup wire together for 114 inches, Jl and 
J2 are RCA female phono connectors. PI is a 
chassis-mounted male octal plug. 



FEBRUARY 1970 



31 



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Any marine frequency (HC6 U) 
80 meter crystals in FT 243 holders 



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Power Supply 

The power source used should supply 
+ 150V and 6.3V with minimum current 
ratings of 50 mA and 750 mA, respectively. 
The high voltage should be regulated. In my 
application a single OD3 regulated supply 
serves both the 6 meter converter described 



Coil Data 



LI 
L2 t L4 

L3. L7 
L5 

L6 



V/i turns No. 2 2 insulated over L2 

Miller 20A687RBI 

Miller 20A827RB! 

Miller 21A155RBI 

5 turns No. 22 insulated over L5 



L3 and L4 spaced % inch center to center 



here and a similar 2 meter converter. The 
high voltage is continuously on in both units 
at all times, and the filament voltage is 
applied to the converter in use. 

Results 

After using the converter for several 
months, I am completely satisfied wilh its 
performance. At no time have I experienced 

problems with stability or the "birdies" 

commonly encountered in VHF converters. 

When the band is open the converter pulls in 

the weak ones, yet does not suffer from 

cross-modulation effects with the locals, If 

you build the converter as shown, I am sure 

that you will be thoroughly pleased. Be 

seeing you on 6. 

. . . WA9HES" 




32 



73 MAGAZINE 



More than 5 million two-way trans- 
mitters have skyrocketed the demand 
for service men and field, system, and 
R&D engineers. Topnotch licensed 
experts can earn $12,000 a year or 
more. You can be your own boss, build 
your own company. And you don't 
need a college education to break in. 

How would you like to earn $5 to 
$7 an hour. . . $200 to $300 a week 
.„ $10,000 to $15,000 a year? One of 
your best chances today, especially if 
you don't have a college education, is 
in the field of two-way radio. 

Two-way radio is booming. Today 
there are more than five million two- 
way transmitters for police cars, fire 
trucks, taxis, planes, etc. and Citizen's 
Band uses— and the number is grow- 
ing at the rate of 80,000 per month. 

• 

This wildfire boom presents a solid 
gold opportunity for trained two-way 
radio service experts. Most of them 
are earning between $5 # 000 and 
$10,000 a year more than the average 
radio-TV repair man. 

Why You'll Earn Top Pay 

The reason is that the U.S. doesn't 
permit anyone to service two-way ra- 
dio systems unless he is licensed by 
the FCC (Federal Communications 
Commission). And there aren't 
enough licensed experts to go around. 

This means that the available li- 
censed expert can "write his own 
ticket'* when it comes to earnings. 
Some work by the hour and usually 
charge at least $5.00 per hour, $7.50 
on evenings and SundaySj plus travel 
expenses. Others charge each cus- 
tomer a jnonthly retainer fee, such as 
$20 a month for a base station and 
$7.50 for each mobile station. A sur- 
vey showed that one man can easily 



maintain at least 15 base stations and 
85 mobiles. This would add up to at 
least $12,000 a year. 

How to Get Started 

How do you break into the ranks of 
the big-money earners in two-way ra- 
dio? This is probably the best way: 

1. Without quitting your present job, 
learn enough about electronics fun- 
damentals to pass the Government 
FCC License. Then get a job in a 
two-way radio service shop, and 
"learn the ropes" of the business. 

2. As soon as you've earned a reputa- 
tion as an expert, there are several 
ways you can go. You can move out, 
and start signing up your own cus- 
tomers* You might become a fran- 
chised service representative of a big 
manufacturer and then start getting 
into two-way radio sales, where one 
sales contract might net you $5,000. 
Or you may be invited to move up 
into a high-prestige salaried job with 
one of the same manufacturers. 

The first step— mastering the funda- 
mentals of Electronics in your spare 
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1 




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1776 East 17th Street. Cfevefand.Ohto 4-411^ 

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He** flying high. Before he got his CIE training and FCC License, Ed Dutaney's only 
professional skill was as a commercial pilot engaged in crop dusting. Today he has 
his own two-way radio company, with seven full-time employees. f 7 am much better 
off financially, and really enjoy my work/* he says. **I found my electronics lessons 
thorough and easy to understand. The CIE course was the best investment I ever made/' 



Business i* booming. August Gihbemeyer 
was in radio-TV repair work before study- 
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t tie easy vvcxy 






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36 













\ ought o ianging various parts and having 

ra he in th inished product dc 
ou. Many peoj included, like to 

c* an i i one md have it w< 

properly h minimum changes. The mor 

the or me ilous the 

1 like to make changes. 

73 MAGAZINE 



Since the average junkbox seldom yields 
all the specified components for any project, 
how are we to avoid unnecessary effort in 
construction projects? After many miles of 
solder joints a method has evolved which I 
believe is the most direct route from circuit 
to finished product^ be it chassis or printed 
circuit board. 




The first step was to evolve a minimum- 
effort method of breadboarding a circuit, 
particularly eliminating drilling, mounting, 
and hardware wherever possible. An arrange- 
ment was sought whereby minimum material 
was used and this material could be used 
over, time and time again for other circuits. 
Another requirement was that the method 
be consistent with good VHP wiring tech- 
niques. 

What followed was an extremely simple 
system consisting of two basic components, 
a piece of copper-clad printed circuit board, 
and a quantity of inexpensive miniature 
terminal strips. The board can be purchased 
at almost any electronic supply house or 
from any number of mail order firms for 
about $2 a square foot. The miniature 
terminal strips are also inexpensive. 

At first a selection of multilug strips 
were purchased as well as the single-lug 
strips; however, after many projects if was 
found that the multilug strips were seldom 
used as most circuits were constructed with 
the single-lug strips. The miniature terminal 
strips are a lot easier to work with than their 
normal sized predecessors, and enable you to 
get a higher component density for a given 
area of copper-clad board. 

The method is simple to use; merely 
decide where on the board a connection is to 
be made between two conductors and 
simply solder down the foot of the terminal 
strip in that spot (see Fig. 1). 

Conductors to be grounded are soldered 
directly to the board. In this manner the 
entire circuit is constructed and changes 
require only the resoldering of a terminal 
lug. I usually keep my component leads as 
long as the circuit considerations will allow; 
after completion of the breadboard phase, I 
can unsolder everything. The components 
are then used in the actual finished product 




Fig, 1. Terminal strips simplify prototyping because 
of the ease with which they can be soldered to a 
copper-clad printed circuit board. (Photo by G. 
Gfrerer.) 



and the terminal lugs can be used again, I am 
still using the same dozen lugs that I 
originally purchased five years ago! 




Once an operable circuit is realized, you 
will no doubt wish to put it in some finished 
form. The most common packaging tech- 
nique is the printed circuit mounting 
arrangement. This appears to be a lot of 
work to the average person, and most of the 
"simple" methods described in articles on 
the subject tend to leave doubt in readers' 
minds. 

After trying many methods I found a way 
which satisfied these basic requirements: 

•Only one chemical required 
•Minimum artwork 

•Minimum time between circuit and 
printed board 

•Capability of small quantity production 

if desired 
•Ability to directly utilize PC layouts 

already in magazine articles 

The key to the entire system is a flexible 
clear plastic sheet which has adhesive on one 
side. This is sold as an inexpensive method 
for plastic laminating of documents. One 
large envelope contains two 8 x 12 in, pieces 
for 99tf.* 

If you would like to build an item from a 
magazine article and the author has printed 
the artwork for his board, you're home free. 
Cut the artwork out, and stick one or two 
layers of laminating plastic on each side of 
it. Take a razor blade and cut out all of the 
conductor areas and remove them. You now 

*Clean-Vu Plastic Film Protector, Sterling Plastics 
Co., Mountainside, NJ. 



FEBRUARY 1970 



37 




^-Feature This 




KHZ 



SIGNAL/ONE'S CX7 GIVES YOU 



Electronic counters belong in the 
laboratory . , . because they're big, 
expensive, precision instruments . . . 
right? So what's one doing in the 
CX7? Well, it gives you ....... 

■ CALIBRATION ACCURACY OF 
100 HZ at every point in 
every band 

■ READOUT DIRECT TO 100 HZ 
. . . without interpolation 



■ • » 



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free of error due to aging or 
environment 

■ BIG, BRIGHT DISPLAY . . . 

virtually impossible to mis-read 

SIGNAL/ONE engineers did it by putting 
state-of-the-art technology to work in a 
precision counter no larger than a small 
book. This remarkable unit actually 
counts each individual cycle of VFO out- 
put during a precise (crystal-controlled) 
1/100 second time interval , . . and dis- 
plays the last four digits of the total on an 

electronic readout, (For example, a VFO 
frequency of 3521,7 kHz (3,521,700 
cycles/second) yields a 1/100 second 
count of 35,217 . ■ ■ and the display 
shows 621.7 kHz). The readout is as 
accurate as the 1/100 second timing. 
Timing is derived digitally from the 100 
kHz reference standard. So, by simply 
zero-beating the 100 kHz oscilator to 
WWV (or a BC station) you automatically 
calibrate the VFO to 100 Hz accuracy . , 
everywhere. 



"It Speaks for Itself" 




A Division of ECI (An NCR Subsidiary) 

2200 Anvil Street No 
St. Petersburg, Fla, 337 






ry) 

Jo, I 
10 / 



have a piece of plastic laminated paper with 
holes in it, which we will call a mask. 

Cut a piece of copper-clad board to size 
and place the mask on the board. Use a 
couple of small alligator clips to keep the 
mask from moving position. Take a can of 
opaque spray lacquer (any color), and using 
minimum paint, spray the board and mask. 
The board and mask should be lying on a 
flat horizontal surface, and you should be 
spraying straight down. 

Be sure to shake the paint thoroughly and 
hold it about 12 in, away from the board. 
Some practice may be necessary in spraying 
to keep the paint from running. The job may 
be done with a series of light sprayings with 
about 5 min. drying time between. Once you 
have finished spraying, lift the mask up 
vertically from the board to avoid smearing 
the paint. 

After allowing the painted surface to dry 
30 min. we can correct any feathered edges 
in the painted areas. These will sometimes 
occur to varying degrees because the mask 
will not usually lay perfectly flat on the 
board. This can be alleviated to some extent 
by using more layers of plastic on each side, 
but it then becomes more difficult to cut the 
mask, A sharpened ink eraser will easily rub 
away smears. 

After the board is prepared to your 
satisfaction, immerse it in a plastic or glass 
tray of ferric chloride or iron perchloride. 
These solutions are now commonly sold in 
supply houses under the description of 

"etchtint" 

The etching time will vary with the 
strength of the etchant, its temperature, the 
thickness of the copper layer, the amount of 
agitation, etc. 

Once the unpainted copper has been 
completely etched away, remove the board 
from the solution. But be especially careful 
to avoid getting any acid on you or your 
clothing! Carefully wash the board with 
lukewarm water and soap. 

The lacquer may be removed by a variety 
of means. The easiest way is to brush on 
lacquer thinner, which removes it very 
quickly. Or it can be removed with steel 
wool or a kitchen scouring pad. 

The remaining copper should be coated 
with solder to protect it from corrosion. 



38 



73 MAGAZINE 



This also builds up the conductive cross 
section. Do this with 60/40 solder and a 
soldering iron. After depositing the solder, 
wash off excessive resin from the board with 
lacquer thinner* 

The only remaining steps are to drill holes 
in the board at the appropriate spots for the 
component leads, and the actual mounting 
and soldering of the components themselves. 
The mask may be stored and used to make 
future copies of the circuit boards if needed. 

What we have done so far is perhaps the 
easiest method, that of using an already 
existing conductor layout. Only a few addi- 
tional steps are needed to design an original 
layout. Plan the conductor pattern on a 
sheet of quadrille graph paper (8x8 squares 
to the inch), drawing in the symbols for the 
components, actual size. Transfer the con- 
ductor pattern below the drawing on the 
same page and use this as your mask, saving 
the original as a guide to drilling holes and 
installing actual components in the board, 

High-Density Packaging 

Sometimes we may wish to get a large 
number of components in a small volume, or 
our circuit has many conductor crossing 
points and does not lend itself well to 
printed circuitry. Classic "chassis" construc- 
tion can be ruled out because by using such 
things as transistor sockets you have most of 
the components under the chassis, and the 
socketed components, transistors or what- 
ever, protrude from the top. This dimension 
from the top of the chassis can be eliminated 
and a saving in space realized. 



HAM HOSPITALITY 





Fig, 2. With a copper-clad hoard as a base plate, 
very high-density packaging can be achieved by 
mounting bulky components, such as miniature 
relays, i-f cans, and crystals, on their sides. This 
receiver section packs 90 components within the 
volume of a 3x5 in. board! (Photo by G. Gi rarer.) 



How about Johannesburg? 

Dan Mahony 2S605 offers his home for visiting 
U.S. hams. His address is 88 Milton Road, Lom- 
bardy East; telephone 60S-1454. Area: 1 acre, (9H 
miles southwest of Johannesburg Centre, Children 
welcome! 

Accommodations: Guest room with private bath. 
Ham shack makes nice spare bedroom for junior 
ops. 
Reciprocity: 1 day, particularly in California area. 

Limited Ham Hospitality 

David G. Fiinn, Starlane Farms, Ridge Road, 
Ludlowville, New York 14862.* 

English speaking DX and U.S, hams welcome. 
Plenty of advance notice requested. We have two 
boys (ages 6 and 8) and 330 acres. Overnight 
accommodations are 10-15 miles away, but we 
could put up 1 or 2 people in an emergency. 
Interests are flying, model railroading, music f and 
art. Wife's tastes: weaving, crafts, music, art. 
Particularly interested in meeting Rotanan hams, 
*Ed. Note. Dave Flinn is owner of SteJIar Indus- 
tries (ham equipment dealer and 73 advertiser). 

My home wilt be open to visiting DX Hams. 

William G. (Jerry) Allnoch WA4TST 
507 Pinecone Street 
Waycross, Georgia 
(912-283-0285) 

Hospitality offered: meals, snacks, and possibly 
overnight accommodations, if they don't mind 
sleeping on a couch in the Itvingroom. 

George Pataki Y02BO/2 
34-24 76th Street 
Jackson Heights, N. Y, 11372 
{212 639-3195) 

Visiting DX'ers; Tour CBS, visit radio clubs, 
meet other hams. I'll serve as your guide around 
town. 



The technique is simple. Using a piece of 
copper-clad printed circuit board as a base 
plate, mount all sockets and major compo- 
nents such as i-f cans on their sides. An 
example of this is the i-f section of a 
receiver, such as that shown in the photo of 
Fig. 2, The transistor sockets are epoxied to 
the board and the i-f cans are soldered to it. 
The minor components are then soldered 
onto the terminals of the sockets and i-f cans 
as required. An inherent disadvantage to this 
type of system is that it is not as rugged and 
cannot take as much physical abuse as a 
printed circuit. 

It is hoped that this discussion will give 
some ideas to experienced builders, and 
encourage the novice to delve deeper into 
this rewarding hobby. 

. . . K1AOB/3" 



FEBRUARY 1970 



39 





THE CAMPER: 



C. W. Wandrey WA9EHE 
915 North President St. 
Wheaton 11 60187 



Mobile and Portable 



More than just a mobile, 

the camper can become 

a base station on wheels, 



One of the things I was anticipating with 
joy when I took an early retirement was the 
additional time that I could spend operating 
my rig. Unfortunately, I also enjoy traveling, 
so, during two years of retirement, my wife 
and I spent only seven months of this time 
at home, Some of our traveling was done 
overseas, but that which we did in the States 
was primarily done in our VW camper. With 
the advent of the many deluxe overnight 
trailer and camper parks throughout the 
country, traveling in a VW camper allows 
one to do a maximum amount of traveling at 
a minimum of cost, a must when living on a 
retirement income! So now our problem was 
how to enjoy traveling and ham radio at the 
same time. One of the things that spurred us 
on to find a solution was the fact that our 
son, in Thousand Oaks, California (W6GST) 
is also a ham and enjoys following us on our 
trips via ham radio. Here's how we worked it 
out. 



40 



73 MAGAZINE 






The ambient noise level in a VW camper 
is relatively high, particularly when driving 
at high speeds. Also, the available space 
below the instrument panel is rather limited. 
We decided that we would limit our mobile 
operating to Citizens* Band and operate the 
amateur bands on a portable basis. The first 
problem to be solved was the antenna 
mount. The standard ones available didn't 
seem to have the desirable mechanical 
strength to allow us to mount a variety of 
antennas (including a full-length telescoping 
vertical for 40 meters. With the use of 
stainless steel (ordinary plated steel or brass 
could be used) and some plastic rod, I 
concocted the mount shown in Fig, 1. We 
normally drive using the Citizens* Band for 
on-the-road communications (Fig, 2). It is 
surprising how many of the long-haul truck 
drivers have CB units in their truck cabs. 
They are usually most anxious to carry on a 
conversation, particularly when they are 
driving the lonely open stretches out west. 
In addition to providing a delightful pastime 
while driving, CB communication can be 
rewarding. Some gas station chains on our 
major interstate highways constantly moni- 
tor Channel 9, which makes them available 
in case one runs out of gas, has a flat tire or 
other mechanical trouble, or-most impor- 
tant—in case of emergency. The Heathkit CB 
transceiver was mounted as shown in the 
photo without any interference with the 
driving controls. It was simple to trim the 
antenna to its proper length with the help of 
a vswr meter and the ground plane area 
provided by the large area of the VW camper 
roof gives about a 5 mile range for reliable 
mobile operation with enough volume to 
overcome the ambient engine noise. 

For operating portable in the ham bands, 
I selected appropriate Heliwhip antennas, 
wound and tuned at the factory for my 
selected favorite frequencies; however, they 
are fairly broadbanded and allow operating 
over a spectrum either side of the specified 
frequency. Pm sure a Hustler or some other 
multiband antenna will be just as satis- 
factory, and it is just a matter of personal 
preference. At home, I use the Heathkit 
SB-301, SB-40L, SB-200 combination, and 
we chose the SB-100 and the Kompact 
Kilowatt HA- 14 for use in the camper. The 



'A £9 *ft 







Fig. 1. Homebrew mount places antenna high above 
the street, yet is stable and electrically sound. 




FEBRUARY 1970 



41 




•— ^— 




1 1 1 1 1 1 • » • • 





Fig. 2, On the open road, the Heathkit CB trans- 
ceiver keeps us in touch with the world. It is com- 
forting to know that one CB channel is monitored 
on a national scale by many of the gas station chains. 

combination icebox and portable sink which 
is standard equipment in Ihe camper was 
removed and replaced with a foam ice chest 
purchased for 88^ and a plastic water jug 
costing less than one dollar. These are 
stowed in any convenient place in either the 
trailer and camper, and to us are actually 
more convenient and flexible than the origi- 
nal equipment. The space vacated by the 
icebox provided an excellent place to mourn 
the radio equipment. To make the installa- 
tion neat and stable we constructed a rack 
(Fig. 3) from some old plywood that many 
years ago had done duty as a Ping Pong 
table. As shown in the photo, adequate 
ventilation must be provided by drilling as 
many holes as possible without impairing the 
strength of the rack. 

Wooden stops are positioned behind the 
two rear rubber feet of the Kompact Kilo- 
watt, the transceiver, and the power supplies. 
This prevents them from sliding to the front 
I rear of the rack); large washers, with off- 
center holes drilled in them, screwed to the 
front of the rack, prevent movement in the 
opposite direction. The height of the shelves 



is such that if the equipment should bounce, 
it will still be held captive by the stops and 
screwed-on washers. The bottom of the rack 
holds a Honda 300W gasoline engine power 
supply. This unit is very quiet in operation 
and surprisingly light in weight, considering 
its output capability. This unit also delivers 
12V dc for battery charging in case of 
emergency, I drilled a small hole to run the 
coax from the antenna inside the camper. 
The hole was then sealed with a plastic 
rubber sealer compound. This made a per- 
fectly waterproof joint- Though most of the 
private trailer parks include free electricity, 
some of the state and national parks do not. 
When juice is available, of course we use it, 
and this allows us to use the full kilowatt. 
When the gasoline power supply is used, we 
operate barefoot. It is quite a sensation to be 
sitting on the side of the highway talking to 
someone several thousand miles away and 
get 20-over-9 reports. 




Fig. 3. Equipment rack replaces icebox of original 
camper, Lots of air holes help to dissipate the heat 
generated by the units, 

Vm sure my wife would rather leave the 
cooking equipment home than the radio 
equipment -especially when we have a 
schedule with our son. 

. . . WA9EHE" 



42 



73 MAGAZINE 



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NOTICE: CALIFORNIA RESIDENTS INCLUDE S PERCENT SALES TAX 



You Think You Have Troubles ? 






Take the case of Charlie Damico W3VXCX 
Charlie is one of our sightless hams. How- 
ever, he has not allowed his handicap to get 
in his way* He is employed in electronics, 
repairs all his own gear, with few exceptions, 
can rig up an antenna without help, and 
seems to get along just fine. 

A few months ago, he began getting TVI 
complaints from one of his neighbors. This 
fellow (who lives in the City of Brotherly 
Love, incidentally) really got hot under the 
collar and began circulating a petition 
around the neighborhood. 

The FCC stepped into the picture and 
investigated the complaints. After finding 
that Charlie was putting out a clean signal 
and was not creating interference on a good 
TV set, a committee questioned the 20 
signers of the petition to find that 14 of 
them thought they were signing a petition 
for someone running for Mayor of Philadel- 
phia. Of the remaining six, four had had no 



interference, but were friends of the original 
complainant; the remaining one was willing 
to drop the subject upon installation of a 
highpass filter. So, Charlie was left with one 
irate neighbor. 

One would think this would be the end of 
the story. Unfortunately, this was not the 
case. One night, Charlie came on the air and 
said, "You know, something seems to be 
wrong here. I'm not getting the right read- 
ings on the output of this rig, and I can't 
figure out what might be wrong/ 1 We all 
noted that his signal was not up to its usual 
strength, but he was still readable. After 
checking his swr, he came to the conclu- 
sion that something was wrong in the 
antenna. He left the air. The following night 
he told us the story. Someone had cut his 
coax feed line to his 75 meter dipole. 

Charlie had gone up to the roof and 
strung a Marconi antenna to get back on the 
air. ... Kayla HaleWIEMV" 



FEBRUARY 1970 



43 



' 




400 




ets you 




frequency- standard accuracy 

with just one crystal ! ! 




shxyws how its done... 



44 



73 MAGAZINE 
















by Gilbert Boelke W2EUP 



A complete and comprehensive arti- 
cle covering theory and techniques 
of indirect frequency synthesis, plus 
schematics and a description of a 
practical 400-channel synthesizer 
used in a two-meter FM transceiver 
with only one frequency-determining 
crystal. 

I 
THE PROCESS 

Frequency synthesis is the term used to 
describe the process of synthesizing (or 
"putting together") many frequencies from 
a small number of starting frequencies. In 
theory, any number of channels may be 
so generated from only one master oscilla- 
tor, using the electronic techniques of ad- 
ding, subtracting, multiplying, and dividing 
frequencies. Tn practice, the larger the num- 
ber of channels the more worthwhile it is 
to' go the synthesizer route. 



A direct synthesizer uses such conven- 
tional techniques directly, filtering the un« 
desired output products at each step in the 
process. This technique has the disadvan- 
tage that many high quality filters are re- 
quired to reduce the undesired (spurious) 
output frequencies to the desired extent, 

An indirect synthesizer uses a voltage- 
controlled oscillator to generate the output 
signal, electronically "steers" it to the cor- 
rect frequency and "locks" it there. Its 
main advantage is that the output needs no 
filtering; it comes from an on-frequency 
oscillator. All spurious products are kept 
within the confines of the synthesizer loop 
(with any luck) and do not appear in the 
output. 

Figures 1 and 2 illustrate two ways a 
synthesizer can be used. In Fig. 1, the syn- 
thesizer covers the full range of transmitter 
and receiver frequencies for a General Elec- 
tric TPL unit. An extra X8 multiplier must 
be added to the receiver so that both re- 



505 Main Street West Seneca, New York 14224 



FEBRUARY 1970 



45 







well it will take someone 
with manufacturing 

"know how" io do it 



But of more importance the crystal must be manufactured 
to Strict Specifications, have good activity and operate 
"on frequency" in the circuit for which it was ordered. 

SENTRY can manufacture crystals for all two-way radio 
equipment: Commercial, Amateur, Aircraft, Military and 
Citizen Band. You need only to specify the model of 
set and channel frequency. 

You don't believe it, when we say - "Buy the Best"? 

You are satisfied with your present supplier? 

You are satisfied with high prices? 

You are satisfied with "second best"? 

Until you try SENTRY you will never know! 

Try Us! Make Us Prove It! "Buy the Best 



.t* 



SEND FOR OUR CATALOG OF PRECISION 
QUARTZ CRYSTALS AND ELECTRONICS 
FOR THE COMMUNICATIONS INDUSTRY. 

IT WILL COST YOU NOTHING! 




SENTRY MANUFACTURING COMPANY 

Crystal Park, Chickasha, Oklahoma 73018 



PHONE: (405) 224-6780 



For Catalog Circle No. 1 on Reader Service Card 





^ J/R SWITCHING V 



FIG, 1 How to use synthesizer for 60 kHz incremental switching in existing units 



ceiver and transmitter multiply the synthe- 
sizer output by 24, to make channel spacing 
the same for both receiver and transmitter. 

Although a synthesizer could be built as 
a crystal oscillator substitute for existing 
types of equipment, it can be more effec- 
tively exploited in a "start from scratch" 
design, as shown in Fig. 2* True FM can 
be produced by direct modulation of the 
synthesizer, eliminating the need for a 
phase modulator or frequency multiplica- 
tion to build up the deviation level. Or, as a 
receiver local oscillator, a synthesizer can 
just as well be designed to deliver the oscil- 
lator injection frequency directly, eliminat- 
ing the need for frequency multipliers. 

Figures 3 and 4 show block diagrams 
representing the synthesizers used in Figs, 
I and 2. The synthesizer block diagram of 
Fig. 3 generates 2.5 kHz steps in the 6 
MHz range. Used to drive existing trans- 
ceivers, this arrangement produces 60 kHz 
steps in the two-meter band. If the range is 
extended to 5.7 MHz and the output multi- 
plied by 24, the same synthesizer can be 
used for the receiver. 

Addition of a mixer and a multiplier as 
in Fig. 4 makes it possible to generate 60 



kHz steps directly in the two-meter band, 
A separate crystal oscillator is used to 
heterodyne the output signal down to a 
frequency suitable for division. By switch- 
ing crystals — in this case to 141 MHz — 
the synthesizer output can be moved down 
9 MHz to provide oscillator injection for a 
receiver having a 9 MHz i-f. These mixer 
injection frequencies could also be obtained 
by suitable means from the basic reference 
oscillator, rather than adding two more 
crystals. 

How it Works 

Consider the simplified synthesizer of 
Fig. 5 . This example is for a 5 — 6 MHz 
output range in 10 kHz steps, A tunable 
VCO ( voltage-controlled oscillator) is used 
to generate the output signal; in doing so, 
of course, it must tune electronically from 
5 to 6 MHz by varying the dc input voltage. 
The stability of such an oscillator doesn't 
even begin to match that of a crystal oscil- 
lator, but it does have the flexibility of 
operating on any channel in the desired 
range. So the remainder of the circuitry is 
devoted to detecting the VCO frequency. 



FEBRUARY 1970 



47 




144 -148 MHz 



T/R SWICHING 



FIG. 2 Synthesis of local oscillator and transmitting frequencies eliminates 
frequency multipliers and greatly simplifies receiver design 



relating it to the desired frequency, and 
adjusting the oscillator electronically to it 

Spacing of the output steps is determined 
by the reference frequency. In this case, a 
10 kHz reference means that the circuit 
can lock to any harmonic of 10 kHz such as 
5.000, 5,010, 5.020, 5.030 . .. etc. to 6.000 
MHz, Direct multiplication could be used 
to get the same result, hut it would be 
nearly impossible to eliminate undesired 
harmonics of the 1 kHz signal, even with 
the best of filters. So, instead of multiplying 
10 kHz to, say, 5 MHz, start with the VCO 
at (or near) 5 MHz and divide it by 500 
instead. This function is accomplished in 
the programed divider (^n 3 or "divide- 
by-ra")« Consisting of a chain of flip-flops, 
this circuit can be programed to divide by 
anv ratio between 500 and 600, When it 
divides the 5 MHz output of the VCO by 
500, the result is 10 kHz. 

The phase detector circuit compares the 
-^n output to the reference signal, deliver- 
ing a dc output proportional to the phase 
difference between them. This dc level 
controls the VCO. When the VCO output 
drifts from exactly 5 MHz, the output of 
the -=-n will drift in exact proportion to it 
since it always is 1 /500th of the output 
signal The phase detector sees this as a 
phase change and shifts its dc output to the 
phase detector immediately to steer it back 
to 5.000 MHz exactly. Since it compares 



phase instead of frequency, the frequency 
at the "na output is never permitted to shift 
so much as one hertz either way, and the 
output of the VCO is held precisely to 
5.00 MHz. Frequency accuracy depends 
only upon the stability of the reference 
frequency oscillator. 

To change frequency to 5,760 MHz it is 
only necessary to change the divide ratio 
of the *r« circuit by switching the program- 
ing inputs of the +n. Since this is a larger 
divide ratio than 500, the ^n output will 

at first be below 10 kHz. The phase detector 
senses this shift as a phase change in the 
very first cycle following the shift and 
immediately starts action to correct it. 
When the correction is complete, the -^n 
output is again on 10 kHz, but the VCO 
is on 576 X 10 kHz, or 5.760 MHz. 

The synthesizer of Fig. 3 is only a little 
more complicated than the basic unit of 
Fig, 5 . Since 2.5 kHz steps are desired, the 
reference frequency must be 2,5 kHz. Stable 
crystals of this frequency are not notably 
practical, so a 1 MHz master oscillator is 
used, divided down to 2.5 kHz by a series 
of flip-flops. A harmonic of the 1 MHz 
signal is conveniently adjusted to zero-beat 
with WWV, thus precisely aligning all chan- 
nels to frequency. A higher divide ratio 
is necessary in the +n circuit due to the 
lower reference frequency, as shown. 



48 



73 MAGAZINE 




i i i i » thJ i ii « 



K t r 

OSCILLATOR 
MHz 





I 



"I I lii ' i » ■■ ■ ■ f ^'Wt^^^^i'l 



~ 2500 




DC STEERING 
VOLTAGE 



OUTPUT, 2.5 kHz 
STEPS 



LOOP 

FILTER 



^^^^^^^*^^^^^^^^ 



I 



I 



'■■■•(■■■^"WP 



— N 

2280 TO 

2480 



2.5 kHz 




FREQ 
COMPARATOR 



2.5 kHz 



*!#HB^^^^"* 



TO FREQ 
SWITCHING 





' " ' " " '' ' "" J 

F/G. 5 Block diagram of synthesizer for use in existing transceivers (see also Fig. 1) 




The loop filter, necessary in all cases, 
must remove all traces of the reference 
frequency at the output of the phase de- 
tector (in this case 2.5 kHz), A simple 
RC low-pass filter configuration is usually 
employed. 



The next step in synthesizer development, 
shown in Fig 4, has a VCO operating in 
the 135 — 148 MHz range, heterodyned to 
the 2—6 MHz range* This mixing process 
is necessary because present-day low-cost 
flip-flops can only divide to about 8—10 



- . . ...■ 






REF OSC 
300 kHz 



VCO 



I 




., . 







— — 




DC 



OUTPUT 1 3 5 - 139 AND 

144-148 MHz 
60 KHz STEPS 



b^^^^^ ..... , . 



LOOP 
FILTER 







I 



MIXER 





XTAL OSC 
150 OR 14! MHz 



60 kHz 



FREQ 
COMPARATOR 




I 



2 T06 MHz 



-N 
40 TO 100 





FREQ 
SWITCHING 



FIG. 4 



Block diagram of synthesizer incorporating a mixer and multiplier for 
generating 60 kHz steps directly in two-meter band 



FEBRUARY 1970 



49 



10 kHz 

REF 

IN 



'•■'•' ¥■■: 



DC 



ummi^m+ 



^^^—^^—^^^^mi 










HW^HMHMiPIMP 



OUT 
5-6 MH2 




FILTER 






^^^*P*^ 



-*- N 
500 TO 600 



10 kHz 
STEPS 



| | | I | 

FREG 
SWITCHING 

FIG. 5 Simplified synthesizer diagram 



MHz in a programed divider circuit. A 60 
kHz reference can be used to generate 60 
kHz steps because the signal is not multi- 
plied in the receiver and transmitter as in 
Fig. 3 , thus simplifying both dividers 
greatly* Frequency stability in Fig, 4 de- 
pends mainly upon the accuracy of the 150 
and 14! MHz oscillators. Frequency adjust- 
ment is necessary in all three oscillators 
with this scheme. Judicious selection of the 
frequency spacing, reference oscillator fre- 
quency, receiver i-f, and the mixer injection 
frequencies can result in a design that uses 
a single crystal. 



The Phase-Locked Loop 

Indirect frequency synthesizers are basi- 
cally feedback systems, where phase error 
is detected and fed back as a correction 
signal. Such a closed loop is called a 
phase-locked loop. As a consequence, cer- 
tain rules must be followed to keep the sys- 
tem stable, as in any feedback system. 

The phase-locked loop must have a loop 
filter at the output of the phase detector to 
prevent rf from leaking into the VCO con- 
trol signal (which should be as clean a dc 
signal as possible). If any rf or ripple ap- 
pears at this point, it will frequency-modu- 
late the VCO. If the ripple is deliberately 
applied as audio, a desired FM signal can 
be produced, Undesired high frequency 
components such as the reference frequency 
will produce spurious sidebands. Thus, it is 



the function of the loop filter to remove 
these undesired products. A second func- 
tion, however, is to determine the phase — 
gain characteristics of the loop, which deter- 
mine its response time, stability, and "cap- 
ture range," 

Capture range is the term applied to the 
maximum frequency difference the loop 

will tolerate between the VCO output and 
the desired output frequency and still lock 
up. Capture range is directly proportional 
to loop bandwidth. The higher this band- 
width, the higher the adjacent spurious 
levels — the lower it is, the closer the VCO 
must be before it will lock up to the desired 
frequency, A low loop bandwidth also takes 
longer to lock up. So a compromise is 
necessary. Despite all of these design cri- 
teria, the loop filter is usually a very simple 
circuit when used in conjunction with a 
good phase detector* 



Phase Detectors 

Since the reference frequency of an in- 
direct synthesizer is typically equal to the 
frequency spacing between channels, the 
phase detector also operates at this rela- 
tively low frequency. The best phase detec- 
tor circuits are those which deliver the 
highest ratio of dc to inherent ac ripple. A 
flip-flop can be used as a digital phase de- 
tector, but its output is quite high in ripple 
content, and it requires a more sophisti- 
cated loop filter than other circuits. The 



50 



73 MAGAZINE 







INPUT 1 

o 


SAWTOOTH 
GEN 


NSM n 


i 


INPUT 2 

o — — 


1 \ 

1 




1 

L 

(CLOSES SW ) 
1 1 1 




PULSE 
GEN 








\J^ 










_l 




FIG. 6 Sample-and-hold phase detection 



best phase detectors in current use work 
on a sample and hold principle. One of the 
two input signals is converted to a saw- 
tooth, the other to a narrow pulse. The 
former is called the ramp, the latter a 
sampling pulse. As shown in Fig, 6, the 
sampling pulse operates a series switch for 
brief intervals so that the value of the ramp 
voltage at that instant is transferred to a 
"holding'* capacitor. If at the next sampling 
time there was no change in relative phase 
between the two signals, the output will not 
change from the first sample. If there is a 
difference, the output capacitor voltage 
shifts abruptly up or down to the new 
value, It can be seen that as long as the 
two signals are in phase lock the output 
ripple is (ideally) zero. With practical im- 
plementation it isn't zero, but it can be 
made extremely low with careful design. 



False Locks 

When the phase-locked loop is initially 
turned on or the frequency is changed, the 
VCO may be out of the capture range of 
the loop. Under this condition the synthe- 
sizer output is that of the free-running 
VCO; unstable and at an unknown fre- 
quency, The VCO must therefore be tuned 
to the near vicinity of the desired frequency 
before the loop will lock up. With most 
phase detectors a number of false lock 
conditions can occur, A false lock is pres- 



ent when the ^n and the reference frequen- 
cies are not equal, but the phase detector 
"thinks" they are and locks the VCO to the 
wrong place. A circuit which assures proper 
acquis itionof the desired frequency is called 
a "search." It acts as an AFC-type control 
of the VCO by detecting frequency differ- 
ences between the s-n output and the ref- 
erence frequency, rather than phase differ- 
ences. The search is normally turned off 
when the phase detector locks the loop, 
There are a number of ways in which a 
search can be implemented. Digital methods 
are compatible with the pulse-type signals 
available, and they offer simplicity of con- 
struction and freedom from adjustment. 
Best of all they are nearly foolproof- 
Circuits 

Except for the advent of low-cost inte- 
grated circuits, this part of an indirect 
synthesizer would probably be impractical 
to build. It consists of a chain of fiip-flops 
whose function is to divide the VCO signal 
down to the reference frequency. The num- 
ber of flip-flops depends upon the maximum 
divide ratio. Since each flip-flop can divide 
by a maximum of 2, two can divide by 4, 
three by 8, etc.; and n flip-flops can divide 
by 2 n . If the maximum divide ratio is 100, 
as in Fig. 4 , it takes 7 flip-flops, which can 
divide up to 2 7 =128* Six would not be 
enough because they can divide by only 
2 6 = 64. In Fig. 3 . a divide ratio of 2240 



73 MAGAZINE 



57 



is needed; 2 n = 2048, too low; 2 l2 = 4096. 
Therefore, 12 flip-flops are needed. 

The next problem is to find some way to 
change the ratio of the "^n by switching so 
that channels may be selected. Two com- 
mon methods are used* To understand 
them, some of the properties of binary 
dividers must be known. First, the divider 
can be considered a counter since at each 
input pulse, or step, the flip-flops take on a 
unique combination of states. A useful 
analogy can be drawn to an automobile 
odometer (mileage indicator), which works 
in a similar way but counts in decades (pow- 
ers of ten) instead of binary (powers of 
two). Including the tenths decade, a typical 
car odometer can count up to 999,999 
tenths of miles, and the millionth step brings 
it back to all zeros. If a switch was pro- 
vided to close only when all zeros are 
present, the switch would close once for 
every 1.000,000 input steps, thus dividing 
by one million. 

One method of changing this ratio would 
be to reset the odometer to zero whenever 
it reached the desired count. For example, 
if a divide-by-567,000 count is desired, it 
could be accomplished by providing a 



resetting device which detects the 566,999 
state, then resets all decades to zero on 
receipt of the 567,000th input. By program- 
ing the desired state when this occurs, the 
divide ratio can be any desired number. 

Another way is to preset a number into 
the divider each time it recycles to zero. 
Achieving a ^"567,000 with this method 
requires that a 433,000 be inserted when 
the counter reaches a natural state of all 
zeros. The counter then counts from 433,000 
to 1,000,000, where it is again preset. This 
count is 1,000,000 minus 433,000, or 
567,000. 

Presetting is the preferred method be- 
cause it is usually easier to implement", 
Desrgn of high-speed ~^n circuits is full of 
subtleties which make it deceptively easy 
to design on paper, but another matter to 
make workable. 

Frequency Display 

Up to about 12 channels, switching and 
display of the channel in use is a simple 

matter. For 30 or more channels it can 
become a problem, because even if a 
30-position switch could be obtained, it 
would be considerably less convenient to 




RCVR 
INPUT 



TO ANT r 



RF 

AMPL 
T1S34 



RF 
AWPL 
54 



MIXER 
T!S 34 



T/fl 
RELAY 



KMTR 
OUTPUT 




9 Mhi 
ftWPt 
US 34 



9 MHi 

AMPL 

TIS34 



2ND 

MIXER 
C A 5028 A 



ISOLATION 
AWPL 
2N9& 



_ 



4»kHl LJ CA30J LJ fi?52 
■FILTER f-F AMPL l LJ-JJ* 



Df&CH 



ZN329Z 
OSC 

a 54* Mm 



CA3020 

AF AMPL 



T 



„4 iw 

AF AMPL 



N0t$E 
AMPL 



RECT 



EMFF 



SW 



I 



155H3a 
VMtt 



SQUELCH 



fft£QU0ICT 
S**T>€SZ£R 




MCXXJUtTQH 



T 



CUPPER 



TO CONTROL 
SW'TOCS 



MH3 



TO T/fl 
RELAY 



2N918 
AMPL 



1 



XMTR 



T/R 

LOGIC 



2N4430 

AMPL 



2N443I 
AMPV 




£0* 

I44-4G 



- — -^ +3 6V REGULATED 



FIG, 7 Block diagram of an FM two-meter transceiver showing how 

frequency synthesis is incorporated 



52 



73 MAGAZINE 













NEW 18TH EDITION OF THE FAMOUS E&E 

t 

Radio Handbook 



by WILLIAM I. ORR, W6SAI 



biggest selling book for the amateur 






Completely revised and updated. 
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City 



Stat© 



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Hi 

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N 
< 

< 



n 
p* 



in 



FIG. 8 Transmit and receive wiring for a typical FM transceiver 











FIG. 9 +9K regulator 



find the channel you want than with only 
12 channels. 

For this reason, switches are usually 
arranged in a power sequence, such as a 
MHz, hundreds of kHz, and (ens of kHz 
arrangement, extended to as many places 
as desired. Tf the -*~n were left in its natu- 
ral state, the switches would have to be 
set in a binary fashion, which could be 
awkward. However, the decade type of 
display is easily accomplished by designing 
the ~^n circuit to work in decades instead 
of straight binary. It takes 4 flip-flops to 
produce a -=~I0 section; cascading three 
such decades results in a capability of up 
to 1000 ehannels.„If the channel kilohertz 
spacing is 1, 10, 100, etc., the frequency 
display is in familiar decimal numbers. 
Other schemes can be worked out for 
different channel spacings, but the decimal 
method is the most convenient, since most 
of us think in terms of decimal numbers. 

It should be kept in mind that the VCO 
output is the output of the synthesizer, and 
even though the loop keeps it exactly on 
frequency, it can't correct for audiofre- 
quency variations (below the loop filter 
response). Even if it could, it would be 
necessary to slow it down for modulation 



purposes; otherwise the loop would attenu- 
ate the audio. Therefore, the VCO of a syn- 
thesizer is as sensitive to microphonics as 
a VFO is, and good VFO construction 
techniques should be used. VCO tuning 
range should just overlap each end of the 
desired output range, and its temperature 
drift should be kept low to maintain band 
coverage. 

The following text describes the synthe- 
sizer used in a 10-kHz-step, 400-channeI, 
144—148 MHz transceiver utilizing a 
single 5 MHz crystal, 

II 

A PRACTICAL 10-kHz-STEP 
SYNTHESIZER FOR TWO METERS 

Figure 7 shows the full transceiver block 
diagram. Output from the synthesizer is 1 
mW in the frequency range of 144— 148 
MHz (transmitter), and 1 mW f 135—139 
MHz. to the receiver first mixer. Modula- 
tion is applied directly to the synthesizer 
for the transmit function, The block labeled 
TjR logic is the circuit board that changes 
the synthesizer output range when the trans- 
mitter is keyed; it also serves to switch the 
receiver and transmitter and drive the 
antenna relay. 



FEBRUARY 1970 



55 



m 




W2EUP f S homebrew two-meter FM trans- 
mitter/receiver looks unbelievably profes- 
sional. The synthesizer controls are the four 
at the right of the panel. The top pair sets 
the receiver frequency, the bottom pair sets 
the transmitter. The basic frequencies of 
operation are selected by the integral four- 
position switches (under the X 100 knobs). 
The frequencies of operation on the pic- 
tured unit are 14634 MHz for the trans- 
mitter (national repeater input frequency), 
and 146.94 MHz for the receiver (national 
repeater output frequency). 



Figure 8 shows the transceiver transmit — 
receive circuits and the system wiring. Two 
power supply regulators are used; one gene- 
rates +9V at 250 mA and the other +3.6V 
at 1A, Nine volts is the B+ level used in 
the receiver circuits, the transmitter modu- 
lator, and the synthesizer, The schematic 
for the +9V regulator is shown in Fig. 9. 

The +3.6V supply is used to provide 
power for the digital integrated circuits, 
which are rated for a temperature range 
of -M5 — +55°C (guaranteed performance). 
Instead of a zener diode, a series string of 

silicon diodes is used as a voltage reference 
for this regulator. This technique produces 
a temperature-programed supply that de- 
livers over 4V when cold and less than 
3JJV when hot. The logic works reliably 
over a very wide range of temperatures 
when operated in this manner. 

Figure 10 shows the synthesizer hlock 
diagram. The single 5 MHz crystal oscil- 
lator drives, through an amplifier, a -^500 
fixed divider to obtain the 10 kHz reference 
frequency, and a dual -frequency multiplier 
section, When in the receive mode, a multi- 
plication factor of X28 is used, producing 
a 140 MHz signal When transmitting, a 
X30 multiplier supplies a 150 MHz signal 



to the mixer. The multipliers are selected 
by the transmit — receive (T/R) logic. When 
receiving, the VCO output range is 135 — 

139 MHz (9 MHz below the corresponding 
transmit frequency). When mixed with the 

140 MHz signal, the mixer output ranges 
from 5 to 1 MHz (140 - 135 = 5; 140 - 
139 = 1) and the ^n divide ratio is preset 
to divide by any number between 500 and 
100, to deliver the 10 kHz output. Since 
10 kHz is the reference frequency, the 
channel spacing is 10 kHz. In the transmit 
mode the mixer produces from 6 to 2 
MHz f 150 - 144 = 6; 150 - 148 = 2), 
and the ~^n is preset to any ratio between 
600 and 200. 

The VCO and VCO amplifier are shown 
schematically in Fig. 11. The B+ to the 
VCO should be kept small to maintain 
maximum tuning range. As it turned out in 
the unit pictured, tuning range was no 
problem and had to be reduced by trim- 
ming the high end of the range with C6* 
The VCO is housed in a section of the 
oven assembly, which also contains the 5 
MHz oscillator and an electronic tempera- 
ture regulator. The VCO itself could have 
been mounted in a nonheated environment 
without stability problems because fre- 
quency drift with temperature turned out 



56 



73 MAGAZINE 










Detail of frequency selection switches show 
how "MHz" section connections are skewed 
1 MHz offset on receive mode. At right an 
extra detent (switch clicking and locking 
mechanism) is reversed and mounted be* 
hind. A I / 8-inch shaft is attached and 
brought to panel through drilled -out shaft 
of front detent. Rear deck is X/00 (hun- 
dreds of kilohertz, front two are MHz 
selection decks, Solderable magnet wire 
was used for connections to keep the wiring 
manageable. 

to be very low, However, in the author's 
transceiver, the oven insulation also acts 
as sound and vibration shielding Cpolyure- 
thane foam), minimizing VCO microphonics. 
Radiofrequency shielding is absolutely 
essential in the VCO. In the prototype unit, 
the VCO amplifier was mounted in a 
separate shielded box, but it was later 
combined with the VCO itself. 

The steer input of the VCO comes from 
the frequency comparator (consisting of 
the phase detector and search) for elec- 
tronic lock* An extra varactor (D4) is used 
to accomplish this by means of a voltage 
supplied from a presteer circuit (described 
later) and switched by the T/R circuits- 
Three outputs are provided by the VCO 
amplifier; In addition to the receiver and 
transmitter outputs, there is a CU mW sig- 
nal fed to the synthesizer mixer for loop 
feedback. The resistor network provides 
some degree of isolation between the out- 
puts. Again, shielding of the VCO amplifier 
is a must. 

Figure 12 shows the frequency multiplier 
section, the synthesizer mixer and the am- 
plifier used to square up the waveform to 
feed the ~^~n circuit. The multipliers are 



conventional and their outputs are con- 
nected in series to feed the mixer. Only one 
multiplier operates at a time, selected by 
the T/R circuits. Grounding the X28 or 
X30 lines selects the desired one. 

Mixer output is amplified by several 
resistance-coupled stages. Transistor Q8 
squares the waveform and Q9 acts as an in- 
verter to provide the two out-of-phase sig- 
nals needed to drive the -=-n circuit. 

The -^-#1 schematic is shown in Fig, 13. 
Note that the divider is sectioned into 
decades I and II and a ~^8 section. The 
terminals shown along the bottom are the 





Top view of unit shows circuit board con- 
struction and "plug-in" accessibility concept 
of two-meter FM transmitter / receiver , The 
two rearmost cards are for receiver. Card 
next to i-f filter is i-f amplifier. The synthe- 
sizer section is shown at right. Left to right, 
the cards are: phase detect and divide-by- 
500; search: diode matrices: divide -hy-n: 
mixer-multiplier. The heavy white leads 
from switches to matrix board are insulat- 
ing sleeves: each sleeve contains 8 — 12 
leads of 32 AWG magnet wire. Slots and 
holes in shields are similarly guarded with 
insulation to prevent the possibility of 
shorts by chafing, 



FEBRUARY 1970 



57 






r 



~i 



5lUHz 




DC 



STEER 



10 



PRE STEER 



M00ULAT10N 
INPUTO 



DC 



r 




L _ ^ I 



r 



n 




-^500 









F35-I49 
MHz 




OUTPUT TO XMTR 



* 144-148 MHz 
" 135-139 MHi 




OVEN 
CONTR 



I I 



I 
OUTPUT TO RGVH 



ImW 



MJXER 



6-1 MHi 



10 KHh 



- H 



' i i 



T/ 






1 1 I 1 1 J. 



FREQUENCY 
SWITCHING 



5MH* 













R SW 



R SW 



L 



J 



F/G, 10 Detail block diagram of frequency synthesizer 



preset inputs. For maximum divide ratio 
(-^800) all of these terminals are biased 
to a positive I — 4 volts and thus no pre- 
sets are inserted. Other divide ratios are 
chosen by selectively grounding (or open- 
ing) these terminals. For example, if Al 
is grounded, it will divide by 799: if BI is 
grounded, it divides by 798; CI grounded 
yields "^796, etc, 

A table of presets is given in Table I, 
showing how the presets affect the divide 
ratio and the resulting frequencies of opera- 
tion in this synthesizer. A zero indicates no 
preset; a "1" indicates a preset on terminals 
Al through C3. Under the +n ratio head- 
ing is shown what happens to the normal 
~^800 ratio as different combinations of 
presets are inserted. For example, a preset 



at Al only (second line) shows a '"I: 
this means that the ratio is reduced by a 1 
from 800 to 799, If 4\ and A 2 were 

both preset, the ^n ratio is reduced by a 1 
and a 10, or 11; therefore, a— 789, Preset 
lines Al to Dl thus switch tens of kihhertz, 
lines A2 to D2 go to the hundreds of 
kilohertz switch, and lines A3, B3, and C3 
go to the megahertz switch, 

A 10 MHz shift is accomplished in this 
design by changing the injection frequency 
into the synthesizer mixer. Since the receiver 
oscillator injection requirement is in the 
135—139 MHz range (to produce a 9 
MHz i-f), a 10 MHz shift is necessary to 
get the output into this range. As previously 
described, this function is accomplished by 
the T/R logic selecting the appropriate fre- 



58 



73 MAGAZINE 









Tomorrow's state of the art today 
THE NEW VARITRONICS/INOUE 



• a 



IC-2F 

AMATEUR 2 METER FM TRANSCEIVER 





All the features of the now famous FDFM-2S are combined with the most up-to-date 
technology and even smaller, smarter styling to make the Deluxe IC-2F an extraordinary 
amateur 2 meter FM transceiver. Look at the specifications of this beautiful, all solid 
state equipment . . . 



TRANSMITTER: RF input power— 20 watts; RF out- 
put — 10 watts minimum; maximum frequency 
deviation — 15KHz (adjustable); Automatic Pro- 
tection Circuit (APC) — NEW! Not offered in 
any other transceiver on the market. Absolute 
assurance of final PA protection from shorted or 
high VSWR antennas by instantaneous trans- 
mitter disabling; Electronically switched — no re- 
lays; Sealed low pass filter to eliminate spurious 
radiation* 



RECEIVER: Double conversion superheterodyne; 
Sensitivity better than 0,4/jV (2 20 db of quiet- 
ing; FET front end; ceramic filters for excellent 
bandpass shaping; Integrated Circuit IF; built-in 
speaker on front paneL 

GENERAL: Six channels (six transmit and six re- 
ceive crystals) selectable from the front panel; 
large RF/"S" meter and easier to read controls; 
power requirements 12 to 15 volts DC 



The Deluxe IC-2F comes complete with high impedance microphone, three-position 
chrome mobile mounting bracket, crystals installed for two channels (Ch, 1, 146.34/ 
146.94; CK 2, 146.94/146.94), power cables and plugs and manual. Amateur Net $349.95 

Optional AC Power Supply with built-in Discriminator Meter, Model IC-3P. Amateur Net 
$49.95 

A vailable at your dealer 

Varitronics Incorporated 

3835 North 32nd Street • Suite 6 • Phoenix, Arizona 85018 
SEE THE 1C-2F AT SAROC IN LAS VEGAS, February 4-8 



— 



s 




OTO RCVR 



O TO MIXER 



PRE5TEER 






> 

a 

N 




a spaced at twice wire dia 
tap: it toc 3 , 2t toc. 



m 



FIG, 11 Voltage-controlled oscillator and associated amplifier 








O+SV 



TO -H 
INPUTS 






FIG, 12 Multiplier, mixer, squaring amplifier schematic diagram 



quency multiplier. However, the MHz pre- 
set must also be shifted by I MHz to receive 
the same frequency as the transmitter is on, 
since only a 9 MHz offset is desired. Thus, 
as seen in the table, the receive presets are 
offset one place in the MHz column. 

The ~^n circuit shown is capable of oper- 
ation to 10 MHz for all presets and repre- 
sents the results of a hard brainstorming 
session. It should be reproducible and will 
work as it is shown, as long as the wiring 
is correct. Unless you understand its theory 
of operation completely it is recommended 
that you simply copy it care fully! Have 
someone else check every connection since 
troubleshooting is difficult. Space doesn't 
allow a complete explanation of its opera- 
tion. 



Frequency switching circuitry is shown 
in Fig, 14. Two complete sets of switches 
allow independent selection of receive and 
transmit frequencies. The diode matrices 
shown permit the use of standard 1 0pposi- 
tion rotary switches. Input voltage for the 
preset lines is provided through the 10K 
resistors. When one of the lines is grounded, 
a combination of presets is grounded 

through the diodes. 

The arm of SI is grounded in the trans- 
mit mode, and the arm of S2 is grounded 
in the receive mode. If SI is in the A posi- 
tion, the transmit frequency is controlled 
by switch set A\ if it is in the B position it 
transmits on the frequency on set B. The 
same is true for S2 on receive. 



FEBRUARY 1970 



61 












» i. 



62 



73 MAGAZINE 




Closeup photo shows that it is practicable 
to get all the components of the phase 
detect and divide-hy-500 circuit onto a 
single small card. 



Figure 15a shows the master oscillator. 
It uses a field-effect transistor and has an 
automatic gain control arrangement for 
high stability. It is completely shielded and 
oven-controlled (Fig. 15b.). - Asterisked 
components are thermally mounted to the 
oven box; the thermistor senses the oven 
temperature, and the other asterisked com- 
ponents deliver heat to it. In the original 
unit, the temperature control pot is mounted 

i 

outside of the oven. 

Referring to Fig. 15c, the 5 MHz low- 
level signal from the master oscillator is 
amplified in Ql and Q2. Output from Q2 
goes to the multiplier section and to squar- 
ing amplifier Q3, which drives the -="500 
circuit. Two outputs are used from the last 
flip-flop fl) 180 degrees out of phase. One 
goes to the search circuit, the other to the 
phase detector, below. The 10 kHz square 
wave is converted to a spike by C6 — R9, as 
seen in waveforms a and b in Table II. Each 
positive spike turns Q5 on momentarily, 
charging CI to +9V. Between spikes 
(waveform r), C7 discharges through R15 f 
producing a sawtooth, (A linear sawtooth 
could be used instead of the nonlinear one 
used here, but the nonlinear waveform is 
actually beneficial in this system and is 
easier to generate. 



These switches provide great flexibility. 
With both switches in the A position, you 
transceive on frequency A* Similarly, with 
both in the B position you transceive on 
frequency /?. Receive A and transmit B, 
receive B and transmit A are other combina- 
tions. It may sound complicated, but this 
system is very easy to use and a beginner 
can master it in seconds* 

Once understanding of the method of 
controlling the synthesizer is complete, you 
can dream up all kinds of ways to control 
it. For example, it is simple to instantly 
select a preset channel, such as 146.94 (the 
national FM repeater output frequency) by 
throwing a toggle switch. This addition can 
be completely independent of other switch 
positions, And remote switching is easy 
because all control lines to the +n circuit 
handle only dc and simply are grounded 
in different combinations. 




Closeup photo shows the search board at 
left, the divide-by-n card and, at right, the 
mixer — multiplier assembly. The wall shield 
between those hoards still in place are made 
from a conducting material deposited onto 
the fibrous hoard material; the close spac- 
ing increases the possibility of card-to-wall 
shorting, so a Mylar insulation sheet was 
attached over the surface of each of the 
shield walls. 






FEBRUARY 1970 



63 



Table L Presets. 





-j-n Ratio 
























Frequency 


Reduction 


Ai 


Bi 


Ci 


Di 


A 2 


B 2 


c 2 


D 2 


A 3 


B 3 


^3 
































10 


-1 


1 

























20 


-2 





1 






















20 


-2 


1 


1 






















30 


-3 








1 



















40 


-4 


1 





1 



















50 


-5 





1 


1 



















60 


•O 


1 


1 


t 



















70 Steps, 


-7 











1 
















80 kHz 


-9 


1 








1 
















































100 


-10 










1 

















200 


-20 













1 














300 


-30 










1 


1 














400 


-40 
















1 











500 


-50 










1 





1 











600 


-60 













1 


1 











700 


-70 










1 


1 


1 











800 


-80 



















1 








900 


-90 










1 


o 





1 








142 






























143 


-100 


















1 








1 44 XMT, 


-200 





















1 





145 MHz 


-300 


















1 


1 





146 


-400 


















o 





1 


147 


-500 


















1 





1 


142 


-100 


















1 








143 


-200 





















1 





144 RCV, 


-300 


















1 


1 





145 MHz 


-400 
























1 


146 


-500 


















1 





1 


147 


-600 





















1 


1 



Sampling pulses are produced from the 
-*-n output in a blocking oscillator (Q3) and 
fed to the gate of Q6 (waveform d). This 
pulse turns Q6 on briefly, charging or dis- 
charging C9 to the value of voltage on CI 
at that instant. Capacitor C9 can only 
charge or discharge through Q6, so it holds 

that value of voltage until the next sampling 
pulse. Different "^n outputs and the result- 
ing voltages across C9 are shown in Fig. 
18, d through /. Transistor Q7 is a source 
follower which drives the following cir- 
cuitry at a low-impedance level, while main- 
taining a near-infinite load on C 9. The 
loop filter consists of R13, C10, R14. R16, 



diodes D5 and D6, and the rf bypasses at 
the VCO, The diodes effectively short out 
R16 for sudden large shifts in phase-detec- 
tor output to speed the lockup process* For 
small changes, as seen when the loop is in 
lock, thev have no effect. 

A bias voltage is developed from the 
high-amplitude blocking oscillator output 
with D3 and D4, This bias is used to hold 
Q6 off between sampling pulses and to 
bias the varactor presteer input on the VCCX 

Figure 16 shows the search circuit. Tt 
operates from the same two frequency in- 
puts that the phase detector uses, except 
that its purpose is to detect frequency in- 



64 



73 MAGAZINE 




Name _ 
Address 
City 



Call 



.State 



_Zip 



□ I enclose 

□ Bill me 



1 yr. . . $6 
10 yr. . . $25 



3 yrs. . . $12 
LIFE. . . $50 



73 MAGAZINE PETERBOROUGH. NEW HAMPSHIRE 03458 | 



■■ 



■iM 



I44Q 



4 50 






1460 



1470 



kJ480 



MHz TERMINALS 




O M 3 



#| o Ba 



+ 9V 



V 



20 30 40 50 



70 80 90 



i0*S kHz TERMINALS 



TO ~N 



►I C 3J 




B, 



0, 



TO-rN 



FIG, 14 



Frequency-switching with 



stead of phase differences, and to coarse- 
tune the VCO to the desired frequency, 
where the phase detector takes over. It 
accomplishes this by checking for pulse 
interlace; that is, to see that for every pulse 
received on one input there is only one 
pulse received at the other input, Obviously, 
if two pulses occur from one input during 



which time no pulse from the other input is 
received, the two pulse trains can't be of 
the same frequency, 

Table HI shows waveforms for the 
locked condition (a. h> c) where the com- 
parator, consisting of gates BCGEHF, etc., 
does not produce any output pulses; and 
where the "="« output is too high in fre- 



66 



73 MAGAZINE 



+9VQ 




D,^D CI IN276 



tOO*S kHz TERMINALS 



r 



^Q 'Q-90 PTS 



I 



A 9 
O- 



^ 



TO 100-900 PTS 



II III 




TO T^rSOAAD 



"I 



147 






5» 
S£T 



^T 



4 



i 

i * 



i| 



"AC 



rc '0-90 PTS 



' II II 






KJTtiHr O 



'A 



](• if 



■ 






TO 100-900 PTS 



II 



^ O ° y* 

"OO'S hHj O 

o yf o 

o 






"1 



(44 i« j* fe 

_5 



V 



-46 



J/We matrices for rotary-switch utilization 



quency (rf, e, /), When this case exists, 
gate H delivers pulses. When the ^n output 
is too low in frequency, gate F puts out a 
series of pulses. When pulses come from 
H, Q6 and Q3 are pulsed on. producing a 
stepwise increase in voltage across C9, This 
voltage is summed with the voltage from 
the phase detector. As it rises, the VCO is 



tuned higher in frequency, which decreases 
the output frequency from the synthesizer 
mixer, decreasing the +n output frequency 
as desired. A correction in the opposite 
direction is accomplished by pulsing Q4 
from gate F. decreasing the C9 charge in 
steps. 



FEBRUARY 1970 



67 



~- 



Gatcs L J, and D do two things: they 
gate the transmitter olT while the loop is 
searching (so you don't search while on 
the air) and they drive the out-of-lock 
indicator light (which tells you when some- 
thing is wrong). The indicator normally 
Hashes briefly between receive and transmit 
If anything goes wrong in the synthesizer 
the light is almost sure to indicate it. 

Transistor Q8 is used as a presteering 
gate: Controlled by the T/R circuit, it is 
biased on in the receive mode, placing a 
positive voltage on the presteer input of 
the VCO, This voltage, adjusted by R16, 
reduces the voltage across varactor D4, 

The oven assembly should he thermally 
isolated to the greatest extent possible. In 
the unit pictured, the crystal oven circuit 
is isolated from the remainder of the cir- 
cuitry hy means of a thick styrofoam sur- 
round. Shown in the oven are: the crystal 
fat left), voltage-controlled oscillator (in 
comer compartment), and 5 MHz oscillator 
with oven control circuit. 




increasing its capacitance and shifting the 
VCO tuning range down. When Q8 is off 
(in the transmit mode) the bias is allowed 
to swing to — 10 volts, which reduces the 
capacitance of D4 to a minimum. Diode 
D9 regulates this bias level. Modulation is 
ac-coupled to the presteer input instead of 
the steer input so (hat it does not interfere 
with the operation of the loop. The 220 pF 
capacitor is an rf bypass. Modulation input 
impedance is 330K. and very little voltage 

swing is needed for 15 kHz deviation. Line- 
arity for this level of deviation is excellent 
and hi-fi audio is possible. 

Transistor Q2 is used to prevent a 
possible hangup condition of the loop, 
where the VCO gets tuned so low that the 
frequency supplied to the ~^n is beyond 
its counting capability. The ^n would then 
start counting erratically, delivering too few 
pulses instead of too many, due to skipping 
pulses. The search circuit interprets this to 
mean that the ^n output is too low instead 
of too high, so it steers the VCO in the 
wrong direction, perpetuating the situation. 
Luckily, the bias supply in the phase de- 
tector happens to depend upon a continu- 
ous supply of +n pulses, so that when this 
hangup condition occurs, it can be detected 
by a large drop in bias voltage. Transistor 
02 is normally biased off by this supply, 
hut when the loop hangs up, bias collapses, 
so Q2 turns on and turns search transistor 
Q3 on in good Rube Gold her ft fashion. 
Transistor Q3 charges C9 to maximum 
voltage, sweeping the VCO to the high end 
of its range, where normal lockup can take 
place. The entire process takes place in 
a few milliseconds. C3 causes a delay to 
make sure that Q3 turns on completely. 

Shielding 

Most of the circuits are susceptible to 
the high-level rf fields typically generated 
by an adjacent transmitter. The *^n circuit 
is an efficient hash generator to nearby 
receivers at nearly any frequency. It is 
therefore important that most of the syn- 
thesizer circuits be shielded from the out- 
side world as well as from each other. All 
leads should be filtered and bypassed with 
RC or LC circuits. Extra B+ bypasses in 



68 



73 MAGAZINE 




o 








3:o 



O 



E 
T3 

C 



5 



C 

o 

J3 



O 

bo 



FEBRUARY 1970 



69 




o o 

Hi y m 

'*'^o: Q .™ 



8. 

ft, 

c 

2 
8 

c 

=3 



5 

Co 



NO 






--■„■ -.- ■;■■ . :,;,. ■■'■ . ..;:■ .,_._; ■•-.-, -v ■ 



70 



73 MAGAZINE 



Table IL Phase detector waveforms. 



(a) 



Cti 



i |— i r~i j—l r~\ r -^r -i_s— i 



*G*H* R£F INPUT 



■ ■ i ' 

04 BASE 



1 I ' I ' ■ ' , ' I 




: 



Hi 



(f) 



tgi 



Ch 



to 



10 *Kt SAWTOOTH (CHARGE ONC9* 



_ 



i 



^ 



SAMPLWG PULSES FO* ^N FREQUENCY =fcfcHi 



Q 7 OUTPUT WITH fdJ INPUT 



I 



1 



1 



1 



J L 



SAMPUNG PULSES FQR- * OUTPUT FREQUENCY TOO HIGH 



J_ 



7 OUTPUT WITH (ft INPUT STAIRCASE UP 



1 



1 



5AMPUH& PULSES POH - N OUTPUT FT^OUtNCT TOO LOW 



1 




\Qj OUTPUT WITH fh) INPUT STAIRCASE DOWN 



Table III Search waveforms. 



Lai 



(bl 



j i 



i i ' i' i'i'i'i'i'i'i'i'i 



DIFFERENTIATED fQ kHi REFERENCE INPUT 

I I I I I I I I I L 



DIFFERENTIATED - N INRJT (LOCKED) 




FLIP-FLOP B-G OUTPUT 



Id) 



.*.< 



r-LTLrL- n I f li-LrLrL-TL- n I I 



(t) 



I I 1 I I 1 I I I I I I I I 



rH iCHFF) INPUT (TOO HIGH) 



GATE B OUTPUT CORRESPONDING TO {d> 




once, and it is truly enough to make a 
grown man cry. Usually, the only hope is 
to open the loop and check individual cir- 
cuits. With experience you can read the 
signs and troubleshooting becomes just as 
easy as robbing Fort Knox. 



Performance 

With a good master oscillator you can 
get counterlike frequency accuracy on all 
channels. The author's unit is accurate to 
better than plus or minus 20 Hz at two 
meters with a 20 minute warmup. Even 
without a warmup period, it is considerably 
better than most crystal-controlled rigs after 
stabilization. 

Unlimited channel flexibility is a recur- 
ring pleasure that intensifies with time. Any- 
one who tells you that you are off frequency 
has just got to be from out of town! Even 
if you have a doubt, it takes only one 
quick zero-beating check against WWV to 
guarantee superaccuracy on all channels! 

The big worry most people have about 
synthesizing frequencies is the potential 
spurious outputs. The author's unit was 
cheked on an H-P spectrum analyzer from 
10 MHz to 2,000 GHz and found to be 
clean to -70 dB from carrier, excepting 
harmonics. And even at that level there 
was only a 5 MHz sideband pair, originat- 
ing from the master oscillator. Adjacent 10 
kHz sidebands couldn't be measured di- 
rectly, but calculations based on the ripple 
level measured in the VCO feedback loop 
indicate them to be over 65 dB down. This 
figure is consistent with on-the-air observa- 
tions. 

Ft is worth the trouble. You must use a 
synthesized rig to appreciate it! 

Gilbert Boelke 



the system will be found helpful in various 
spots. The most insidious form of system 
trouble is when complex circuits interact in 
ways not anticipated: so make sure the cir- 
cuits function as they should separately, 
and then combine them in sections. Test 
everything for proper function before mak- 
ing any attempt to close the loop. When the 
loop is out of lock, everything jumps at 




And They'll All Wear Green. . . 

The Annual St, Patrick's Day Swapfest, organ- 
ized by the Midland Amateur Radio Club, is slated 
for March 14 and 15. Write MARC, Box 967, 
Midland TX 79701 for details. 



FEBRUARY 1970 



71 



ENCODING & DECODING 






. . . a series of three re fa ted articles 



PART I: 



Encoders for Subaudible, 
Tone-Burst, or Whistle-On Use 



by John Gallegos W6ZCL 
14646 Flatbush Ave. 
Norwalk CA 90650 



PART II 



Tone Decoder for Remote 




itching Applications 



by Ken Sessions, Jr. K6MVH 
73 Grove Ext. 
Peterborough NH 03458 




PART 



Setting Up the Tone -Burst 
System 



by Les Cobb W6TEE 
4 1 24 Pasadena Ave. 
Sacramento CA 95821 



72 



73 MAGAZINE 




Editor's Introduction; 

An interesting and unforeseen problem 
developed as a result of the tremendous 
growth in popularity of FM repeaters: When 
two or more repeaters operate with overlap- 
ping coverage on the same input or output 
frequency, mobile operators occasionally 
find themselves triggering more than one 
repeater. The mobile operator who does so 
may thus cause interference by his uninten- 
tional keying of the repeater in a neigh- 
boring community. 

As a rule, shifting the frequencies of one 
of the repeaters is no solution, because both 
relay stations will want to be on the nation- 
ally accepted standard (146.34 MHz input, 
146.94 MHz output). Such standardization 
is a boon to the mobileer who has a limited 
supply of crystals and must travel across the 
country or from one area to another once in 
a while. 

But there are workable solutions. More 
and more, repeaters in highly congested 
areas are going to a "tone-burst entry" 
approach or a "whistle-on" system of key- 
ing. With a whistle-on system, the control 
circuits are all at the repeater site. The 
repeater is never operative unless specifically 

activated by one of the users. 
A broad whistle on the input frequency ener- 
gizes a decoder at the repeater site, which in 
turn activates the automatic signal-relaying 
system. Typically, the repeater stays on, 
once activated, retransmitting the signals of 
all carriers on the input. When the traffic 
dies down a bit— that is, after a short period 
of no signals -the repeater shuts down again-, 



and cannot be used unless someone deliber- 
ately calls for it by whistling on the input. 

When multiple-repeater conditions are 
more severe, the tone-burst keying system is 
the more satisfactory solution. Here, a speci- 
fic tone frequency— usually 1700 to 2000 
Hz— must be present briefly at the outset of 
every transmission before a signal can be 
automatically relayed. In practice, all who 
intend to use the repeater will install simple 
audio oscillators into their transmitters, con- 
necting them in such a way that the tone 
comes on briefly each time the transmitter is 
keyed. The tone, decoded at the receiver of 
the relay station, is used to activate the 
repeater— but only for the duration of a 
single carrier. 

The first article in this series of three 
describes how whistle-on and tone-burst 
repeater systems are used and presents sche- 
matics of a simple oscillator suitable for use 
in whistle-on systems as well as a "micro- 
encoder" that can be adapted to either 
lone-burst entry or subaudible continuous- 
tone squelch systems. The second article in 
the series gives construction and theoretical 
details for a decoder ideal for use with either 
of the two single-tone oscillators of Part I. 
The third article, by Les Cobb, describes a 
network of tone-burst repeaters, and in- 
cludes information on how to set up a 
tone-burst oscillator in a mobile transmitter 
and how to connect a decoder into a 
repeater system, Together, these three articles 
provide complete information for convert- 
ing an existing repeater facility to tone access. 



FEBRUARY 1970 



73 



■ 




Part I: 




by John Gallegos W6ZCL 



Encoders for 



Subaudible, Tone-Burst, 
or Whistle-On Use 



The FCC sanctions the use of semicontrol 
techniques such as continuous-tone carrier 
squelch systems (very low frequency tones 
accompanying all carriers) and single-tone 
(tone-burst entry or whistle-on access) in 
applications where limited access to a re- 
mote station or a repeater is desirable. The 
W6FNO repeater in Southern California 
went one step further, and the result is a 
repeater that is fully compatible with two- 
way nonrepeater operation taking place on 
the input channel. 

In many ways, the W6FNO repeater at 
Radio Ranch could serve as a model installa- 
tion: The repeater stands ready for use 24 
hours a day and is never shut down where it 
cannot be accessed by a station on the input 
frequency. On the other hand, the repeater 
will shut itself off if a three-minute period 
elapses with no signals on the input. Sounds 
a little contradictory, but it isn't-not really. 
The W6FNO repeater was an experiment to 
test the concept of subcontrol, i.e., limited 
control of the repeater from the actual 
frequency of operation. 

The repeater is equipped with two timers. 
The first timer is a transmission-limiting 
device: when the input carrier exceeds three 




Barely more than a 
thumb's width j the 
W6ZCL phase-shift 
oscillator is small 
enough to he pack- 
aged within the case 
of almost any com- 
m ercially available 
hand-held trans- 
ceiver. 



minutes duration, B+ is removed from the 
transmitter final; and it can only be re- 
applied after the input carrier drops out 
momentarily. The second timer removes the 
transmitter B+ also. But in this case, the 
timer is activated by the absence of an input 
signal. Since the shutdown is only B+ re- 
moval, the repeater is ready to be activated 
immediately upon application of the proper 
signal, which in this case is nothing more 
than a shrill whistle. 

The W6FNO repeater is a "talkback 
type, as opposed to a "prime" repeater. A 
talkback repeater uses a national FM channel 
as the input frequency and a nonactive 
channel as the output. A prime repeater uses 
a nonactive channel as the input and an 
active, popular frequency as the output. The 
popular 1 46. 34-to-l 46.94 repeaters across 
the country are primes. If the frequencies 
were reversed, they would be talkbacks. 

The active FM channel for direct non- 
repeater operation in the W6FNO territory is 
146.82 MHz, which also serves as the re- 
peater input. The repeater output frequency 
is not used at all except by stations who 
want to hear what*s going through the 
repeater. When two stations are conversing 
on the FM channel, the repeaterus not even 
a part of the operation unless one of the 
operators wants it to be (as for instance 
when the copy gets rough). 

When a user wants to monitor the active 
146.82 channel, but he is too far away from 
the area of activity to hear the stations, he 
merely puts a carrier on the channel and 
whistles into the microphone. Instantly the 
repeater comes on, regardless of the time of 
day or night, and the user finds himself right 
in the middle of the action. The only 



74 



73 MAGAZINE 






THE BEST DEAL IN OUR HISTORY ! 




The National NCX-500 with its AC-500 cur- 
rently sells at $425,00 and $99.00 respectively. 
Thus, this deal is both timely and thrifty. If 
you have waited because you could not afford a 
modern rig, here is your buy now; even while 
the rest of the worfd goes up on price. 

Since we opened our door we have never had 
such an attractive ham opportunity! 

We offer to hams, world wide, the famous 
National NCX-500 transceiver new at the 
thrifty price of $249.95. With the companion 
AC-500 power supply the total price is only 
S299.95; tess than the price of America's most 
popular kit. 

Here are the salient features of this deal: 

a) Only new -factory cartoned material 

offered, 

b} A full six months warranty provided. 

c) No trades considered at these prices. 

d) Prices quoted are FOB Harvard, Massachu- 
setts. 

e) Bank Americard, Master Charge or Amer- 
ican Express charges accepted. Financing 
available through GECC subject to their 
acceptance of your credit. 

f\ Special overseas prices available to sterling 
customers. Remember this set works on 230 
volts 50 cycles equally welL 
g) Offer limited to first come first served, 
{Although we bought them all they will not 
last long.) 



If you are a beginner or even if you have a big 
rig and need a second one for a spare, the 
NCX^500 should be your cup of tea. Study the 
specs, read the magazine reviews but send in 
your order while our stocks last. 



SPECIFICATIONS 
Frequency Coverage: 14,000 - 14,500 kHz, 
3,500- 4,000 kHz, 21^000-21,500 kHz, 
7,000-- 7,300 kHz, 28,500 - 29,100 k Hz. 

(Two additional crystals available at $7.00 each to 
provide expanded coverage of entire ten meter band) 



Price schedule: 

NCX-500 with AC-500 (no spkr & no cabinet) S299 ,95 

INJCX-5Q0 with NCXA supply (spkr and cabinet in- 
cluded* $319.95 

IMCX-500 with Linear Systems Universal Mobile power 
supply 400-12 ...... $359*95 

NCX-500 without supplies $249.95 

XC-23 plug in solid state Xtal calibrator (available 
February 15th, 1970) . S 19.95 



Power Input: -500 watts PEP on side band; 360 watts 
on CW; 125 watts on AM; Derated 20% for mobile 
operation. Emission: SSB upper on 10, 15, and 20 
meters; Lower on 40 and 80. Output Impedance: 
40-60 ohms minimum pi network. Receiver offset 
tune: By means of a varanor controlled oscillator vou 
obtain plus or minum 3 kHz, SSB Generation: Crvstal 
lattice filter 6-50 D6 shape factor 2.2-1, gate 2.8 kHz 
on 6 DB; center frequency 5.202 MHz; uses stable 
solid state ring modulator. Dial Calibration: 5 kHz on 
all bands. Tuning Ratio: Excellent mechanical resolu- 
tion with 45-1 rate. Electrical Stability: Nominally 
1,500 cycles in first thirty minutes. Thereafter, plus or 
minus 400 cycles for room ambient. Suppression: 
Carrier minus 50 DB, rejected side band minus 40 dB, 
third order products minum 30 dB at full Output. 
Sensitivity: .5 microvorts for 10 dB s/N m SSB mode. 
Audio Output: Better than 2 watts into 3.2 ohms. 
Metering: PA cathode current in transmit, S units on 
receive. Special Features: Includes side tone monitor- 
ing plus built in code practice oscillator for novices; 
incremental tuning; provision for crystal calibrator. 
Dimensions: 6-3/16" high by 13-3/8" wide by 11" 
deep. Weighs but 15 pounds. Accessories Available' 
AC-500 21 pounds; NCXA 25 pounds; 40f>12 DC 
supply 13 pounds; AC supplies operate on either 117 
or 234 VAC 50-60 cycles; suitable for export; Mobile 
bracket and instructions furnished at no extra charge. 
Shipments: Preferably via United Parcel Service, Rail- 
way Express or Parcel Post. Specify and include 
provisions for same otherwise charges will go COD. 

HERBERT W. GORDON CO. 

"America's Largest Exclusive Ham Store" 

Woodchuck Hill Road 
Harvard, Massachusetts 01451 »(617) 456-3548 | 




1 12V tf » W* 



I6K 





2N2S59 




3£ P F 



Q * 



16 K 



Fig. J-h Single-transistor tone oscillator for tone- 
burst or whisile-on use produces 1 ISO Hz at 
sufficient amplitude for most transmitters, 

difference is that he hears the 146.82 action 
on some other channel. 

The decoder at the repeater site that 
provides the turn-on function is nothing 
more than a simple frequency-to-dc con- 
verter such as the semiconductor decoder 
shown in the second article of this three-part 
series (included with this issue). This device 
is set to respond to as broad a range of 
frequencies as possible without being ener- 
gized from ordinary conversations. 

Even though the W6FNO decoder was set 
to respond to a wide frequency range, a few 
users found it difficult to key the repeater 
on by whistling. Perhaps their audio levels 
were not quite what they should have been 
to reproduce properly the required tone 
(1750 Hz), or perhaps they were simply not 
proficient whistlers. At any rate, I decided 
to install a simple automatic whistler in each 
of my transmitters. 

The circuit is the epitome of simplicity: a 
single-transistor oscillator using a twin-T 
feedback network. As can be seen from the 
circuit of Fig. 1-1 , a few minutes and a good 
junkbox are all' that is required. 




MOTOROLA 

CONTROL 

HEAD 



Fig. 1-2. A momentary-contact switch can be used 
as shown to interconnect the encoder audio into 
the mike line at the control head for whistle-on 
applications. 



I didn't connect the whistler so that it 
would go on with each transmission. Not 
only would this have defeated the purpose 
of the repeater's automatic-off function, but 
it would have given my signal the unpleasant 
characteristic of a squeal at the outset of 
each transmission. Instead, I connected the 
device into the transmitter so that it is 
energized by pressing a momentary-contact 
switch on the control head. Figure 1-2 shows 
how the oscillator is interconnected into my 
Motorola mobile unit. 

The oscillator circuit shown in Fig. 1-1 
works for tone-burst entry applications, too, 
where the tone frequency tolerances are not 
particularly critical. But the interconnection 
would have to be a little different from that 
shown in Fig. 1-2. For tone-burst operation, 
remember, the audio note must appear for a 
short period every time the transmitter is 
keyed. A timing circuit for accomplishing 
this is shown in Part 3 of this series, Les 
Cobb*s article entitled "Setting Up the 
Tone-Burst System/' 

Where the tone frequency is critically set, 
decoder instability is intolerable and whis- 
tling won't quite cut the mustard. For such 
applications, the encoder requirements be- 
come quite stringent. But it is possible to 
build a highly stable encoder unit with a 
minimum of parts. The circuit described 
below, for example, represents a very versa- 
tile transistorized encoder that can be built 
small enough to use with hand-held trans- 
ceivers, yet stable enough for the most 
demanding applications normally associated 
with FM two-way communications. Because 
of its tiny size, I call the device a "microen- 
coder," 

A particularly attractive feature of the 
microencoder is the fact that it can be used 
for either continuous-tone squelch* (com- 
monly known in these parts as PL, for 
Private Line), or for tone-burst entry. As 
noted in the editor's introduction to this 
series, a continuous-tone squelch scheme 
utilizes a subaudible very low-frequency 
note, whereas the single-tone method de- 
pends on generation of a fairly high- 
frequency note. Most low-frequency en L 
coders require vibrating reeds for stability; 
the one described here is a notable excep- 



76 



73 MAGAZINE 




R 9 
300 



I 
t 

t 

I 



Q 



4-9V {3 mA) 



ALL RESISTORS l/4W t 5% 




+ 12V 



TO PTT 



RELAY 



2N2369 



47 uF 

20 V 



VERNIER FREQ ADJ 
ADJFOR FREO WHILE COUNTING 




87 TO 112 Hz 
2V P-P 



8 



OI*F 



J2 



5K (output W: 

LEVEL) 



+< { TO AUDIO AMPL 

I DEV CONTR) 
I 

I 



Fig. 1-3. Schematic diagram shows basic circuit as used in a continuous-tone-squelch repeater access 
system. Parts values shown are not applicable to single-tone encoder applications (see text). 



Figure 1-3 is the schematic diagram for 
the unit, which is essentially a phase-shift 
oscillator coupled into an emitter follower. 
Since the power consumption of the oscil- 
lator circuit is so low, a standard 9V 
transistor-radio battery will provide an ideal 
power source. At full output, the oscillator 
draws no more than about 3 mA. 



Table I. Parts Lists for CTS and Single-Tone Systems 



Component 


87— 112 Hz 


1750 Hz 








range 




R1 






10 pot 

* 

(multiturn) 


50K pot 
(multiturn) 


R2, 


3. 


5 


10K 


47K 


R4 






10K 


22K 


R5 






10K 


47K 


R6 






5.1 K 


5.1K 


R7 






5K pot 
(multiturn) 


4.7K 
5K pot 










(multiturn) 


R8 






300C2 


300ft 


R9 






0.1/iF 


0.001 fiF 


C1. 2. 


3 




47 M F, 20V 
tantalum 


47 fxF, 20V 
tantalum 


C4 








1 /xf 


C5 






0.01 /t F 


tantalum 


Q1 






2N930 


2N930 


Q2 






2N2369 


2N2369 



Table I shows two complete parts lists. 
The application of the encoder (continuous- 
tone squelch or tone-burst entry) will deter- 
mine the parts selection for your particular 
use. 

The very small size and the apparent 
simplicity of the microencoder might logical- 
ly lead you to suspect its performance. But 
these factors notwithstanding, the device can 
produce a very healthy looking sine wave, as 
can be seen from the photo of Fig, 1-4. 
Laboratory temperature cycling tests on the 
three units that I built indicate that the tone 
output will remain stable and will not drift 
more than 0,5 Hz over the range of 25-60°C. 
My units were built using disc ceramic 
capacitors, incidentally, substitution of 
Mylar capacitors for (1. 02, and C3 will 
undoubtedly result in even better tempera- 
ture stability. 




Fig* 1-4. Scope trace shows the sine wave obtained 
with the author's encoder unit. Increments shown 
are 2 msec per centimeter for the horizontal scan 
and 500 mV per centimeter for the vertical scale. 



FEBRUARY 1970 



77 





Photo shows three separate packaging schemes: printed-circuit 
layout; "cordwood" technique, and the * 4 crystal-can'* method, 
using a conventional Pomona Electronics miniature mounting box. 



The schematic shows transistor Ql to be 
a 2N930, but this type was chosen arbitrar- 
ily because it is something I happened to have 
"kicking around." Actually, any good NPN 
will suffice, as long as it is a type with a beta 
of 100 or so. The transistor used for the 
emitter follower is even less critical, and can 
be effectively duplicated with just about 
anything in the junkbox that has the same 
polarity. 

As a continuous-tone-squelch encoder, the 
one mounted in my 41V has proved quite 
capable of keeping me communicating 
through the local toned repeater, which uses 
a GE KT-5 decoder to open the squelch with 
an input of 88.5 Hz. Another of the units, 
built from the other parts list, of course, 
very efficiently provides me with a 1750 Hz 
tone burst when I operate through the 
W6FNO repeater. 




Fig. 1-5. Actual-size reproduction of printed-circuit 
iayout. The copper side of the board is shown; 
components all mount from far side. (There is no 
copper on the component side.) 



Figure 1-5 is a circuit board layout 
shown actual size. Figure 1-5 is for 
those of you who intend to do the job up 
first class with printed-circuit wiring. The 
printed-circuit version looks sharper, of 
course, and it has the added advantage of 
ending up with a slimmer overall profile. The 
layout shown in Fig, 1-6, however, is per- 
fectly satisfactory for "brass-board" models. 
This version requires nothing more than a 
few holes and some standoff terminals on a 
flat piece of almost anything. 

The dimensions of the boards are suitable 
for mounting the completed unit inside a 
Pomona Electronics Model 2417 shielded 
box ($L50 at practically any self-respecting 
electronic sales outlet)* The low-frequency 
version that I am using is mounted on the 
inside rear chassis wall of my mobile 41V, 

LEGEND* 

© GROUND STAWOFF 
• INSULATED STANDOFF 

© INSULATED FEED THROUGH 
MATL: BRASS OR COPPER-CLAD PC BOARD 



(FREQ ADJ] 



R* C 1 C 3 R 



-<GND 




< J l (+9V) 



J 2 (TONE OUT) 



St LEVEL ADJ) 



Fig. 1-6. Wired-board layout was designed for use 

with Sealectro push-in Teflon standoffs and ground 
terminals. Transistors can be held in place by 
TO-18 heatsinks, (Heatsinking is actually unneces- 
sary. The cases of the transistors are hot and must 
be insulated from ground; the heatsinks perform 
this job by virtue of their anodized finish.) 



78 



73 MAGAZINE 



immediately above the transmit crystals, I 
use miniature coax to apply the dc supply 
voltage (9V) and to cany the 88.5 Hz signal 
to the deviation control potentiometer 
through a 500 k£2 resistor, as shown in Fig. 
1-7, If space is not available in the radio to 
mount the Pomona box ? the printed-circuit 
board itself can be mounted in any available 
underchassis spot. The two variable resistors 
can be replaced without detriment by fixed 
resistors after the proper values have been 



SUGGESTED CONNECTION TO XMTR 



OSC 



40 



-# TO MULT STAGES 



PHASE 
MODULATOR 



i>-r@ 



50OK 



TO-J2 

ON' ENCODER 



.01 



-, PI 

DEV S4-lnh6" 
CONTR > > — ' 



AUDIO 
AMf»L 



/77 



Fig. 1-7. Schematic showing manner in which the 
low- frequency version of the phase-shift oscillator 
can he tied into the transmitter. 

■ 

determined for your particular frequency 
and output-voltage leveL But potentiometers 
are handy if you have the space. If you can 
use them, I suggest the use of the miniature 
multiturn devices (Bourns Trim pots), be- 
cause of the vernier tuning they afford. 

The parts Lists shown in Table I cover the 
continuous-tone-squelch range of 87-112 
Hz and the single-tone frequency of 1750 
Hz, For those whose requirements are not 
met by either of these sets of values, the 
frequency of the encoder may be calculated 
from the equation 



f = 



1 



2tt\/6RC 



0.085 
RC 



If the single-tone version is used rather 
than the continuous-tone-squelch version, 
the audio need not be coupled to the 
transmitter as shown in Fig. 1-7. At these 
higher frequencies, it is practicable and 
convenient to simply mount the encoder 
unit inside the control head and connect the 
audio output lead from the oscillator direct- 
ly onto the mike Line. If you choose to 



BAND PASS ANTENNAS 





i 




Return Loss Response Band Pass Response 



50 MHZ to 52.5 MHZ 

8element-12 DB 

142.5 MHZ to 149 MHZ 

7 element-10 DB 
9 element— 13 DB 

11 element- 15 DB 

220 MHZ to 225 MHZ 

9element-12 DB 

400 MHZ to 500 MHZ 

12 full wave elements— 1 1 DB 
21 full wave elements— 13 DB 

Baluns for above antennas 



$39.95 

14.95 
19.95 
24.95 

$14.95 

$19.95 
$29.95 

$5.00 each 



Do-it-yourself Insulator Kits 
with instructions: 504 per element 

All prices FOB Stockton 

SWAN ANTENNA COMPANY 

646 N. Union Box 1 122 464-9897 
Stockton, California 95201 



adopt this method, just connect a 200O 
resistor in series with the tone oscillator 
output lead before attaching it to the carbon 
mike pin on the control head connector. 

If the local repeater is the whistle-on 
variety (rather than tone-burst entry) > you 
might also find it convenient to run the 
audio lead through a single-pole switch 
mounted on the control head. In this way, 
you can switch the tone on whenever you 
want it, and keep it out of the circuit the 
rest of the time. (A whistle-on repeater stays 
on after the tone is applied for a few 
milliseconds, and does not drop off the air 
until several minutes after the repeater is not 
occupied,) 

For tone-burst entry applications, the 
timer circuit described in Part III will prove 
very worthwhile. With the addition of this 
simple timer, the oscillator can be made to 
key on briefly with each initiation of the 
push-to-talk circuit. (Again, a tone-burst- 
entry system requires a short fixed- 
frequency tone to accompany each incoming 

signal to be repeated.) 

* 

. . . W6ZCL" 



FEBRUARY 1970 



79 




'art III h' Ken Sessions. Jr. K6MVH 




Tone Decoder 
for Remote Switching 




The most critical element of a tone-access 
system is the decoder. When some problem 
exists in the encoder, or when the encoder 
frequency shifts a bit or when the encoding 
level goes up too high or down too low, the 
control operator can solve the problem with 
a few local adjustments. But when the 
decoder starts acting up, the impact can be a 
great deal more severe: In the first place, the 
decoder is installed at the repeater site, 
which is, more often than not, situated atop 
some remote mountain peak—miles (and 
sometimes hours) from physical accessibil- 
ity, Second, while an encoder malfunction 
affects one individual's operation, a decoder 
problem affects the operation of every user 
of the repeater. Thus, care in building and 
sound conservatism in design are paramount 
considerations in deploying a tone control 
scheme, 

I have had occasion to use many decoders 
during my days of remote control and 
repeater operation -some homebrew, some 
commercial. {Virtually every aspect of 
remote control involves the installation of a 



tone decoder somewhere along the way. And 
I can truthfully say that I have never come 
across a circuit that offered performance 
superiority over the one shown in Fig. 2-1. 
I hasten to add that I can lay no claims as 
to design, for the circuit illustrated was 
conceived, built, debugged, and perfected by 
Bob Mueller (K6ASK), of Alhambra, Cali- 
fornia. Nor is this the first time the circuit 
has been published, I have incorporated 
copies of the circuit in past articles dealing 
with remote control of telephones, function 
selection in repeaters, and coded signaling 
for selective-call applications. It simply is a 
good sound circuit and can be applied 
wherever there exists a need to perform a 
switching function in one place by radio 
command from another place. 

Decoder Requirements 

The response curve of the decoder must 
be selective enough to preclude the possibil- 
ity of off-frequency signals triggering the 
system, yet broad enough to allow decoding 
under a variety of input signal conditions. 







NOTE C 1.0 01 TO 5^F 

DEPENDING U^ON 
FtEOUENCf iEOUiKEO 



Fig. 2-1 Single-tone decoder. 



80 



73 MAGAZINE 



Ideally, a control should be available so that 
the threshold sensitivity of the decoder 
could be adjusted. 

Adjustment of the input sensitivity 
accomplishes the effect of narrowing or 
broadening the spectral response of the 
device. At the least sensitive setting, the 
decoder has an input bandwidth of about 50 
Hz. As the serie^ resistance to the input of 
the transformer is decreased, the bandwidth 
widens. In the most sensitive position, the 
decoder will respond to a bandwidth that 
includes random noises and high-pitched 
voices. Thus, the decoder should fulfill the 
requirements of the whistle-on crowd as well 
as the more critical needs of the tone-burst 
fans, 

The frequency of the decoder, using the 
values shown in the schematic, is 2300 Hz. 
This frequency can be shifted by the expedi- 
ent of changing the value of capacitor CL 
The 2300 Hz is fully appropriate for tone- 
burst applications, where voice tripping is to 
be avoided and whistle-on use discouraged. 
(The frequency is high enough to make 
whistling a difficult method of access,) It 
should be reemphasized, however, that 
whistle-on use of this decoder is possible- 
using the values shown— by simple adjust- 
ment of the sensitivity control of the input 
transformer. 

Interconnection 

The simplest part of getting a tone-access 
system to work is the interconnection of the 
decoder itself. All you have to do is provide 
the proper power to drive the transistors and 
relay, then connect the speaker audio from 
the repeater receiver to the low-impedance 
input of the decoder. After that, it is simply 
a matter of making a few adjustments with 
respect to level (at the decoder input and at 
the receiver output). When the controls have 
been properly set, an incoming tone of the 
correct frequency will cause the plate relay 
in the decoder to close. Use of the relay's 
contacts is a matter that is best left to the 
judgment of the repeater owners. If you're 
short of ideas, however, you might just read 
on. Part III tells how to go about setting up 
a complete tone-burst-entry repeater system. 
And the decoder described here will fill the 
bill nicely for that application. 

. . . K6MVH" 



MARRIAGE 




. . , she wants to give you a divorce so you can 
marry your ham radio equipment. " 



73 BINDERS 

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Swan 350 w/AC supply console 
Swan 350 both sidebands — xtal calib. 

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FEBRUARY 1970 



81 



Setting Up the 
Tone-Burst System 



Among the various techniques for selec- 
tive control of remote devices, including 
repeaters, one of the simplest is tone-burst 
keying. This method consists of a short burst 
of a specific audio tone automatically sent at 
the start of a transmission, In a repeater 
application, a burst detector (see Part II of 
this three-article series) is used in conjunc- 
tion with the carrier-operated relay to acti- 
vate the repeater transmitter upon reception 
of the proper burst frequency, and to hold it 
on as long as the incoming carrier is present. 

The simplicity and versatility of tone- 
burst keying should not be overlooked 
where a simple control or selection function, 
not related to primary control, is required. 
As an example, the number of 146.34~to- 
146.94 repeaters on the air or being built in 
Northern California and Nevada was such 
that it became obvious that overlapping 
input coverage was going to cause uninten- 
tional keying and Interference to adjacent 







(*) REPEATERS 
* SIMPLEX 



Fig, 3-1, Tone-burst entry plan— 34/94 
repeaters— No, CalifJNevada, 



machines. To obviate this, a tone-burst 
frequency allocation plan was agreed upon. 
As shown in Fig. 3-1, the plan covers four 
repeaters and one remote base station with a 
burst-protected 146,94 receiver. 

While it is admitted that the tone-burst 
approach does not solve all of the problems 
associated with overlapping repeater cover- 
age, it certainly tends to minimize them by 
permitting the users to call for only the 
particular repeater needed for a given two- 
way communication exchange. 

If tone-burst entry is used on open 
repeaters on the nationally adopted fre- 
quency of 146,34, some semblance of stan- 
dardization should be maintained to give 
travelers some hope of universal access capa- 
bility, Partly because of the abundance of 
Motorola equipment, the frequencies long 
considered standard by Motorola are most 
common in amateur use. The following 
frequencies are stock outputs for the Moto- 
rola P-9301A encoder: 1800, 1950, 2100, 
2250, and 2400 Hz. 

In amateur service, there are many tone- 
burst systems operating in the 1700 to 1800 
Hz range, but these lower frequencies might 
better be reserved for whistle-on use because 
of the ease with which they can be orally 
reproduced. 

For those wishing to use commercial 
equipment, the Motorola P-930IA encoder 
and P-9303 decoder are available on the 
surplus market. More recently, the Motorola 

SP-1005-TAAE solid-state under-dash oscil- 
lator has become available. This unit has a 
selector switch and can generate all tones 
from 1800 to 2400 Hz, in 150 Hz incre- 
ments. 

But if youVe a mind to build up the 
encoders and decoders, the circuits shown in 



82 



73 MAGAZINE 



i 1 



OLD RELIABLE 




i 



hi 
Vmi 



ESSCO's Complete 

Sotrt State RTTY DEMODULATOR. 



-i% f 



W-i. 



TU-78 DUAL CHANNEL KIT 

TU-7 (As above) Factory wired, tested & guaranteed 

TU-7C SINGLE CHANNEL Kn 

TU-7D (As above) Factory wired, tested & guaranteed 



$138.25 
$163.00 
$132.25 
$156.25 



Mo.Je! TU 7C 



" Oeletype Specialists 

324 ARCH STREET CAMDEN. N. J 



Phone (609} 365-6171 



the accompanying articles should do nicely. 
That leaves only the problem of intercon- 
nection. 

When an encoder such as the one 
depicted in Part I is used, some means must 
be employed to limit the oscillator's output 
to no more than a half-second or so with 
each keying of the transmitter. To accom- 
plish this, the timing circuit shown in Fig, 
3-2 was developed by K6GUC, In his 
approach, the 12V supply for the encoder 
must be keyed on and off with the trans- 
mitter. 

At the repeater site, some wiring must be 

done at the decoder to keep the transmitter 
locked on for the duration of a carrier,even 
though the tone itself drops out. Figure 3-3 




OSCILLATCW 



r 




I J 

CAREER OPER- 
ATED RELAY 



TONE- BURST DECODER 



Fig. 3-2. K6GUC tone-burst timer. 



Fig. 3-3, Burst decoder and carrier-operated relay- 
connections. 

illustrates how this might be easily achieved. 
The repeater control relay (K2) should be 
fairly husky; it can be driven directly by the 
decoder relay <K1). It is not wise to derive 
the K2 switching functions by wiring the 
contacts of Kl directly, because KI's con- 
tacts are likely to be of a delicate nature. K I 
is a sensitive, current-operated relay and its 
contacts are best used for no greater require- 
ment than to control a heavy-duty dc relay. 

. . . W6TEE ■ 



FEBRUARY 1970 



o3 



- 



HOW 




VISIT 
FOREIGN 
COUNTRIES 




by Wayne Green W2NSD/1 




MoRfeu-,e> 



A reader, about to make a trip abroad, 
asked for hints on how to get in touch with 
amateurs in foreign countries. As one who 
has done this sort of thing a lot, I think I 
have some helpful ideas. 

First, by way of preparation, I devote 
several weeks to intensive activity on 20 
meters, I look for contacts in the countries I 
am about to visit, and I find that these 
contacts almost invariably lead to interesting 
invitations to dinner and sightseeing. They 
also lead to my getting to meet many more 
of the local amateurs. 

I follow up my contacts with a QSL card 
and a letter giving my itinerary in detail for 
my trip. If I am going to be met at the 
airport, I try to make sure that my DX 
contact knows just what flight I will be on, 
and I let him know immediately of any plan 
changes. I realize that he will be taking a lot 
of trouble on his end, rearranging his work 
schedule, his family plans, and setting up 
meetings with friends, so I try to be as 
considerate as I can. If I am not traveling a 



long distance, I phone ahead and let him 
know that I am on schedule. 

It is well worth while to write ahead to 
the secretary of the national amateur radio 
club of the country you are going to visit. 
The club officer can arrange for you to meet 
a representative and this often leads to 
introductions to local amateurs, visits to 
club meetings, and even getting in touch 
with someone to stay with on occasion. 

If you are interested in operating, the 
club can often help you to get an operating 
permit and may even have a club station 
available for you- If you use the call letters 
of the station, often no permit is required 
and all you have to do is just sit down and 
operate. I have done this from dozens of 
countries. Always offer to take care of the 
QSLing brought on by your operating. 

Rare Countries 

There are very tew rare countries where 

there is not even one active amateur. If you 

are going to DXpedition to a completely 

inactive country, you will have to bring 



84 



73 MAGAZINE 



along your own equipment, obviously. This 
is expensive and difficult, as any reading of 
articles by DXpeditioners makes very clear. 
For my part I avoid countries of this rarity 
and try and stick to those that have at least 
one active amateur. 

1 have found that the amateurs in rare 
countries are all too happy to have me visit 
and sit down for a day or so at their rigs and 

rack up a few thousand contacts. The 
pressure for contacts and more contacts 
every time they get on the air gets to be 
depressing after a while, and they tend to 
limit their operating time or keep out of the 
American phone band. In just a couple of 
days I can take a lot of this pressure off. 

English is the native language for very few 
DX operators, so I find that under QRM 
conditions I can make contacts many times 
as fast as can the local op. Knowing English^ 
I can sort out call letters quickly from the 
mass of calling stations. 

Even when I visit relatively common 
countries I find that I get pileups. When 
operating from 5Z4ERR in Nairobi I gave 
contacts to a lot of the lower power stations 
that normally miss out on DX. Further, I 
found that I was in great demand by mobile 
ops by the dozens. My system of working 
right down to the weakest signal in each call 
area made it possible to work even the 
flea-power stations. 

When 1 visited FK8 I found that the 
country was in great demand because almost 
all of the local ops spoke only French. The 
FK8 ops appreciated my getting a few 
thousand W*s off their backs by giving them 
a contact with their country, Ditto F08 in 
Tahiti. 

Your trips abroad will be infinitely more 
fun if you make arrangements to visit 
amateurs. They will wine and dine you, 
show you their city and country, just as you 
would them # They will offer to put you up 
and they will get in touch with friends in the 
cities along your path. You will have an 
opportunity to explain the U.S. to them in a 
way that no Hollywood movie has ever 
done. You will also have a chance to find 
out anything about their country that you 
want to know, just for the asking. And they 
will love you for being interested enough to 

ask - . i . W2NSD ■ 




5th Annual National Convention 

QTH...STARDUST HOTEL, Las vegas, nv 
QTR... February 4-8 , 1 970 




Cocktail Parties by 
Ham Radio Magazine, SWAN, GALAXY. 
Ladies Luncheon Program. 

SECOND NATIONAL FM MEETING 

Technical seminars; meetings by 

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HOSTED BY SOUTHERN NEVADA ARC, INC, 



Tell our advertisers 

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in 73 



WHERE DO YOU FIT? 

The FCC regulations give as the' purpose of 
amateur radio: 

(a) Recognition and enhancement of the value 
of the amateur service to the public as a voluntary 
noncommercial communication service, partic- 
ularly with respect to providing emergency com- 
munications. 

(b) Continuation and extension of the amateur's 
proven ability to contribute to the advancement of 
the radio art. 

(c) Encouragement and improvement of the 
amateur radio service through rules which provide 
for advancing skills in bot the communication and 
technical phases of the art. 

(d) Expansion of the existing reservoir within 
the amateur radio service of trained operators, 
technicians, and electronics experts. 

(e) Continuation and extension of the amateur's 
unique ability to enhance international good will. 

Where do you fit? 



FEBRUARY 1970 



85 



mmm 








Warren MacDowell W2AOO 
1 1 080 Transit Road 
East Amherst NY 1 405 1 











Many of us, when we first started in 
amateur radio as a Novice, purchased the 
Heathkit DX-35, This transmitter was capa- 
ble of 75 W input and was running quite hard 
to achieve this power level. The oscillator 
and final were both keyed, so with certain 
crystals there was an inherent chirp. 

We were contemplating the use of the 
DX-35 as a CW exciter for a kilowatt linear. 
Our main goal was to modify the circuitry of 
the DX-35 to improve the efficiency and 
eliminate the chirp. 



■O B + 



*5K 






BOmF 
450v 



15K 

IOW- 



80 \if 
450v 



nr 



Fig, 1 . Existing 20 jJlF capacitors can be replaced 
by 80 fJF cans to up the filtering to 40 fJlF total 



The first modifications to be made were in 
the B+ filtering circuit. Normally, two 20 /iF, 
450V capacitors were being used in series to 
give a total of 10 jiF, 900V of filtering. We 





replaced these paper capacitors with can 
type 80 juF, 450V capacitors to give a total 
of 40 juF for filtering (See Fig. I). Appro- 
priate holes were cut in the chassis so as to 
mount the can type capacitors. One of the 
capacitors will require an insulating mount 
to isolate it from the chassis due to the fact 
that these capacitors are in series. The 
original equalizing resistors (15 kf2 ? IOW) 
were retained and placed in parallel with the 
new capacitors. 

The 5U4 rectifier was replaced with a 
1N1239 silicon rectifier unit. This solid state 
rectifier plugs directly in the socket of the 
5U4. (An alternate method is to build up 
your own replacement in the base of a 
broken 5U4.) You conserve on power trans- 
former drain through the use of this because 
the 5 V filament source is no longer neces- 
sary. The solid state rectifier will also pro- 
vide an increase in total plate voltage. 

We had received reports of chirp using the 
DX-35 as a barefoot transmitter. Of course 
this would be undesirable when using the 
linear. A considerable voltage drop was 
observed on the oscillator plate when the 
transmitter was keyed. Also, both the final 
and oscillator are keyed, We removed the 
cathode grounding lead of the oscillator 
from the front panel keying jack and ran this 
to a single-pole toggle switch that was also 



86 



73 MAGAZINE 



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AHOI Comptete -Monovtable Flip Flop KiL..40 
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A9054 Delay Line 10 40 usee Imp. 20000 Ohms 
A2031 Miniature variable Capacitor 3 75 uufd . . 



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Dual 2 input gate ..... 1.00 

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JK Flip Flop 1 00 

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Buffered JK Flip Flop . ,1.00 
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Motorola PNP Germanium 

Power 55 Waits 75 

RCA PNP Germanium 

Power 7.5 Walls , T5 



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BOX 1, LYNN, MASSACHUSETTS 01903 



mounted on the front panel. This switch was 
wired so as to ground the oscillator cathode 
and allow the oscillator to run at all times 
when the final was keyed. Less chirp was 
noticed but there was still a small amount 
present. 






osc 



003 



0D3 




220K 
IW 



diodes were placed in series to give a 300V 
regulation level. Resistors (220 kfi s IW) are 
paralleled across the 0D3's to equalize the 
voltage and a 5 kS2, 10W current-limiting 
resistor was placed in series with the OD3's 
(Fig. 2), This assembly was inserted between 
the oscillator B+ and chassis ground. The 
voltage on the 12BY7 oscillator now remains 
at 300V during the keying sequence, and 
the chirp is eliminated. 



i 



ioo 

IW 



I 



4pF 
350V 



Fig. 2. The 220 kO resistors across the series regula- 
tors help to equalize the oscillator voltage distribu- 
tion. 

The next step was to get rid of the 
voltage variation on the oscillator that was 
present when keying. Two 0D3 regulator 



Fig. 3. Keying shaping circuit. 

Though not really necessary, we added a 
keying shaping circuit consisting of a IQOO, 
IW resistor in series with a 4 /iF, 35 OV 
capacitor. This circuit shown in Fig. 3, goes 
from the keying "hot" lead to ground. 

* . - W2AOO" 



FEBRUARY 1970 



87 






Sergio Lovisolo IISLO 
Via Ravina 70, 
Malnate, Varese, Italy 




PANORAMIC RECEIVER 
FOR VHF 



O 




. . . Lets you see the whole band at once 



h 



One of the more typical aspects of my 
father's (I1LOV) personality is that he wants 
something new in his ham shack every day, 
and this requires a lot of brainwork from 
me, to satisfy his never ending need for 
strange gadgets, 

A few evenings ago, he was as usual 
having his complicated QSOs on 2 meters, 
tuning the band with three different 
receivers at the same time, when he said, 
"How nice if 1 could take a look at the 
complete band, and know every moment 
what goes on the air," 

There was no possibility of mistakes! I 
lighted a cigarette, as usual, before I went to 
explore in the junkbox and began to work. 



A day later, there was the panoramic 
receiver, with his calibrated scale showing up 
every signal on the 2 meter band. And now 
the complete story. 

The first approach was quite fast. 1 took a 
generator, injected a sweep signal in the 
socket of the crystal in the local oscillator of 
the converter (144-28 MHz), connected the 
oscilloscope to the last i-f in the receiver, 
and in a few minutes I had the band on the 
screen (Fig. 1), But the local oscillator 
wasn't working properly, and sensitivity 
wasn't very high. 

If you are a lazy fellow, have a scope and 
a sweep generator, and a few extra con- 
verters for the various VHF bands, this is the 



88 



73 MAGAZINE 



job for you. For me, it was nice to see that 
1 everything worked as it should, but I was 
sure that there was a simpler approach, one 
requiring no modifications in the converters, 
and giving the possibility of hearing and 
seeing with only one antenna and one 
converter. So, it was clear I had to work on 
the tunable i-f receiver. But you cannot put 
your hands in the station receiver, especially 
if it is a 75 A I or 51 SI, as it was in our case; 
so, there are two possibilities; you have 
some old i-f receiver around, or you build it. 
Fortunately, I found an old receiver I had 
made some years ago, a double conversion 
I unit with no rf stage in it* 

I disconnected the tuning capacitor from 
the local oscillator coil and connected a 
varicap diode in parallel. A wire from the 
sawtooth generator in the scope furnished 
the sweeping voltage, A few more modifica- 
tions to the detector and first audio stage, 
and the output of the receiver went to the 
vertical plates of the oscilloscope. After a bit 
of tuning, the panoramic receiver was ready 
to monitor the 2 meter band. 

Principles of Operation 

A few words to explain how it works for 
those who are not acquainted with oscillo- 
scopes, sweep generators, and panadapters. 
In every oscilloscope the trace you see is the 
result of the rapid sweep of the luminous 
spot across the screen which is produced by 
a sawtooth voltage applied to the horizontal 
plates. Now if you apply an ac voltage to the 
vertical plates, the spot will be subjected to a 
double force, one compelling it side to side, 
and the other up and down. Let us assume 
that the frequency of the alternating voltage 
driving vertical plates is two times that of 
the horizontal ones. Then in the time it 
takes to go from left to right, the spot will 
be deviated up and down twice, and will 
show a two-period sample of the voltage 
under examination. 

Now, if the vertical plates of the oscillo- 
scope are connected to the detector of the 
receiver, a signal will appear on the screen 
every time the receiver is tuned to a station. 
Now, imagine tuning across the band very 
fast -exactly as fast as the spot on the screen 
runs on its way from left to right. If you 
tune a full megahertz while the spot makes a 



trip, you will see a pip on the scope every 
time a signal is tuned in. This is due to the 
fact that the signal generates an output 
voltage only during the short time in which 
its conversion frequency allows it to pass 
through the narrow bandpass of the re- 
ceiver's second i-f. If you tune from 5 to 
6 MHz, the left side of the screen will be 
5,0 and the right side 6.0. Every signal will 
show up on the scope in a place on the 
screen in direct relation to its frequency. 
Now the problem is that you cannot 
manually tune your receiver up and down. 
This function is provided by a Variac, to 
which is applied the same voltage that 
sweeps the trace. This provides synchroniza- 
tion between the scope and the receiver local 
oscillator. 



Circuit Description 

The receiver circuit is quite conventional 
and requires only a little care in isolating the 
circuits working at different frequencies to 
prevent spurious responses that will appear 
as pips on the screen- The input signal is 
link -coupled to the grid coil of an ECS 8 
triode mixer. (You can use a 6AM4, or 



2&-30 RECEIVER 




RF OUTPUT 



Fig. 1. Block diagram. Above, first assembly: 
sweep on VHF converter. Below, connect the 
sweep scope on vertical input to the last i-f trans- 
former with a 5 to 15 pF capacitor. 




» 



a/ispf 



f 



TO VERT 
INPUT 



> DET 






LAST I.F, TRANSFORMER 



FEBRUARY 1970 



89 







SAW TOOTH IWPUT 

4fBVPP 



L1 -Primary, 8 turns 26 AWG close wound 3/8 in. 
slug-tuned coil. 

Secondary. 3 turns 26 AWG close wound. 
L2 — Primary. 2 turns 26 AWG on cold side of 
grid coil, 1/2 in. slug-tuned coil. 

Secondary, 7 turns 26 AWG close wound, 



L3-10.7 MHz M transformer. 

T1, T2, T3, - 455 kHz if transformers. 
All resistors 1/4W except otherwise noted. 
D1 capacitors are mica or ceramic disc. 



Fig. 2. Schematic of the panoramic receiver. 



something like that; any rf triode will work.) 
A BA 102 (5-15 pF range), driven by a 
sawtooth voltage coming from the scope's 
sweep generator, is connected across the grid 
coil of a 6J4 local oscillator, sweeping its 
frequency from 2L120 kHz to 23.120 kHz 
to provide a first i-f of 6.8 kHz. A 6U8 
second mixer local oscillator converts this 
signal to 455 kHz with a quartz crystal 
resonating at 5.425 kHz* I was compelled to 
use such unusual i-f frequencies by the 
crystal I had on hand. You can try other 
combinations, but be sure you don't use a 
first local oscillator frequency starting at 24 
MHz; otherwise, you will have a spurious 
response at 144 MHz that will probably be 



heard by your VHF converter. The same 
care in selecting the second oscillators 
quartz crystal must be used in order not to 
have spurious responses in the 28-30 MHz 
range. Two 6BA6 stages at 455 kHz provide 
plenty of gain and are very stable, showing 
no tendency toward oscillation. One diode 
section of a 6AT6 tube is the detector, I he 
other provides a little age, while the triode 
section is the video preamplifier. You can 
omit it and use a crystal diode if your scope 
has amultitube vertical amplifier, B+ voltages 
are provided by a GZ34 full-wave rectifier. 
As you can see from the photo, screening is 
provided between rf and first i-f stages and 
455 kHz i-f section. 



XO 




TO SCOPE VERT AM PL 



YO 



Fig, 3. Output section. 



90 



73 MAGAZIME 








Top view of panoramic receiver. 

Construction Details 

You can get an idea of the disposition of 
the various parts by looking at the photos. 
(The tuning condenser and the screened tube 
near the last i-f transformer are no longer in 
use, due to the fact that the receiver was 
built as a normal audio unit.) As you can 
see, the power transformer is a very big one. 
You can simplify the supply without degrad- 
ing the performance of the receiver. This will 
allow you to use a smaller chassis. 

The positions of the various components 
are not too critical, and you have only to be 
careful thai you make good ground connec- 
tions and use good quality bypass capaci- 
tors. As shown in the picture, I used a lot of 
big old mica capacitors from surplus strips. 
In the rf and i-f stages, connections should 
be as straight and short as possible. Bypass 
every hot filament pin. Coil L3 is a 10.7 
MHz i-f transformer, and you must modify it 
to tune around 7 MHz. Take the coil out of 
its can and parallel small-value capacitors to 



S <^1 


Emm9k*ummm1 HI 

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radio amateur 1 


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Bottom view of unit. 



HATRY ELECTRONICS 

500 Ledyard St., Hartford, Conn. 06114 

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CONNECTICUT'S OLDEST HAM STORE 



FEBRUARY 1970 



91 



■ 



im 



the internal ones, if any, until you find 
resonance around 7 MHz (with the slugs half 
in) on a grid dip oscillator. After that, you 
can close the cans again. (Mine tuned with 
50 pF,) 

The crystal controlled local oscillator is 
very simple, with nearly nothing to tune, 
and starts without any difficulty. Coupling is 
provided by a I pF capacitor from pin 9 to 
pin 2. A few twisted turns of wire work 
equally well, The i-f amplifier, having a very 
high gain, requires a little care. Short wiring, 
bypass capacitors connected to the i-f trans- 
formers where the leads enter the cans, and 
eventual shielding connected across the tube 
sockets will keep everything quiet. 

My receiver was built on a normal chassis 
(that of an old S-102 Hallicrafters 2 meter 
receiver), but the second time, I found that 
it is much easier to build converters and 
little receivers on printed circuit boards. 
They are easy to drill, offer a very good, 
easily soldered ground, and you can readily 
make a chassis of any dimensions you want, 
and begin to build while you wait for the 
box to be made. 

Tuning Up 

First, connect the vertical amplifier of 
your scope to the video output of the 
receiver. Then, with no B+ on the 6U8, 6J4, 
and EC88 tubes, connect a 455 kHz gener- 
ator to the grid pin (2) of the pentode 
section of the 6U8 tube, and tune all the 
slugs in the 455 kHz i-f transformers (begin- 
ning from the last one) for maximum height 



of the trace. Keep the output from the 
generator as low as possible, consistent with 
a readable trace on the scope. Too much 
output will cause distortion, and no more 
trace height. Repeat two or three times. 
Next, connect B+ to the 6U8 tube. The local 
oscillator should start immediately. Connect 
the generator, tuned near the first i-f fre- 
quency (6,88 kHz in our case) to the grid 
pin of EC88 tube, and try to get an output 
(be careful not to tune on the image, which 
is about 900 kHz lower than the funda- 
mental. Tune the slugs in L3 and trimmer 
capacitor from pin 9 of EC88 for maximum 
output. Now disconnect the 10 kfi resistor 
in parallel with LI and tune it at 29 MHz 
with a grid dip oscillator. Find the sawtooth 
generator tube in your scope. Normally^ 
when the sync selector is in the internal 
position, the output from this tube is con- 
nected across the ^horizontal gain" poten- 
tiometer. Be sure that there is no high 
voltage on this control. With a VTVM or a 
scope, verify that there is 5-10V of the 
sawtooth voltage between the hot side of the 
potentiometer and ground. 

If everything is right, connect a shielded 
wire from the hot side to the "sawtooth 
input" in the receiver. Now, connect B3 to 
the EC88 and 6J4 tubes. With the generator 
connected at the antenna plug tuned at 29 
MHz turn Rl (sweep width control) till you 
see a pip on the center of the screen. Rotate 
the sweep frequency of the scope till you get 
the narrowest pip. (Sweep frequency must 
be as low as possible, around 30-60 



144,000 



ffl 




BAI02 
VARlCAP 



E" MIXER 
J/2 6U8 



455 



IF AMP 
2 6BA6 



VIDEO DET 
AMPL 
6AT6 



L.O 
1/2 6 US 



o 



VERT 
INPUT 



F 



fh 



Fig, 4. Block diagram, final assembly 



SAWTOOTH OUTPUT 



H0R GAIN 
C0NTSOL 



92 



73 MAGAZINE 



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HzJTune around with the generator and 
notice how many MHz you are seeing on the 
scope. If the sweep is too wide or too 
narrow, rotate Rl till you get the wanted 
width. Now, with the generator again at 29 
MHz, recenter the pip on the scope, turning 
the slug in LI, Repeat the preceding steps 
several times, till you get the wanted band- 
pass. 

If you are not interested in the center 
frequency being at the center of the screen, 
with slight adjustments, you can put 28 MHz 
at the left side and 30 MHz at the right side 
of the screen. (Naturally, if you want, you 
can select other frequencies, from about 26 
to 32 MHz just tuning the slugs, with up to 
4—5 MHz bandwidth.) Now, tune L2 for 
maximum response at the center of the 
trace, and select a swamping resistor that 
gives an equal response in every point of the 
trace. Usually, the 10 kO unit marked on 
the diagram will do, depending on coil Q and 
the desired bandpass width. 




I 

m 






1*5 

Scope trace 






Now you can calibrate the screen with a 
frequency scale. As you can see from the 
photo, the scale is not linear, as in any 
capacity-tuned oscillator. Another source of 
nonlinearity can be an irregular sawtooth 
tension. Differences often found in inexpen- 
sive varicaps make it difficult to track 
oscillator and antenna coils, The first time, I 
tried to track L2 with another varicap fed 
with sweep voltage (you can see two little 
black controls near LI), but that resulted in 
sweep noise coming into the station receiver, 
and this approach had to be abandoned- This 
happens when the 2 meter converter used 
for the pan adapter and the receiver is the 
same. 

Now you can connect the output of your 
VHF converter to the panoramic receiver 
and see the band. If there is too much 

"grass, 71 it is better to reduce it, detuning the 
last i-f transformer a little instead of re- 
ducing the vertical gain on the scope. 

On-the-air Performance 

It is possible to see many signals just 
above the noise level. (In the photo you can 
see six). The panoramic view proves useful 
on many occasions— to have an idea of 
activity on VHF, while working other fre- 
quencies, for roundups, for turning the 
antenna to the best compromise position in 
a multisided QSO, to tune VHF converters, 
for zero beating, etc. 

The best part: I got a reprieve, of sorts. 
This toy has kept my father busy enough 
that he's lost the kick for something new 
every day. 

...I1SL0" 



FEBRUARY 1970 



93 



■ 





for Hams 



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STUDY GUIDE 

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73 MAGAZINE 



WAMXX 



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CIRCUITS 

HANDBOOK 

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Vol. L This book is largely a collection from FM 
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The material is taken from the editions of 
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Vol. II. This book contains selected technical and 
construction articles taken from FM Maga- 
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73 Magazine 

Peterborough, N. H. 03458 



FEBRUARY 1970 



w 



«— . 



Kay la Hale W1EMV 

Box 224 

Dublin NH 03444 



VARIABLE-IMPEDANCE 

MOBILE 




By far the most popular mobile antenna 
is the center load coil variety. These come irf 
various sizes, shapes, and colors* depending 
upon the whim of the manufacturer 
The New-Tronics model, for instance, comes 
in a quiet shade of gray, and depending upon 
power rating and frequency, varies between 
about W and 2" in diameter. Waters Manu- 
facturing favors black for the color and has 
an assortment of shapes for the coils. 
Webster has recently come out with a new 
KW series. The coils are white in color; They 
are sometimes referred to as the "White 
Bubble." 

Each of these has its advantages, and 
efficiency varies from band to band. So it is 
highly possible that one might use different 
coils and tips for different bands. In my 
particular case, the Webster KW-80 has 
proved very successful for 75 meter opera- 
tion. However, on a long trip, multiband 




COAX FROM RIG 



% 



Y 



\k 



lOOOpF 



K 



o 400pF 

m 

COAX FROM BASE MOUNT 



J, 

(SI-3 POSITION CERAMIC SWITCH) 

Fig. 1. Schematic diagram. 

operation using the Waters 75 meter coil 
with the Band- Adder (see Dec, *67, 73 
Magazine) makes it possible to operate 
10-15-20 and 75 without getting out to 
change coils. 

Waters and New-Tronics claim a 52 ohm 
match and require no further matching 
device. Webster suggests the use of some 
type of impedance matching on 80 and 40 
meters. Tests have shown that a 1,000 pf 

silver-dipped mica capacitor from the center 

conductor to ground provides a good 

impedance match on 80, and a 400 pf 

capacitor provides the proper match on 40. 

No matching is required on 10-15 or 20 

meters. Now, let's face it — connecting and 

disconnecting capacitors at the base of the 

antenna every time you want to change 

bands becomes Excedrin Headache No. 74. 

After knocking heads with Bill 

McCracken, K1GUU, we came up with this 

nice little switching arrangement. In this 

case ? a deck mount is used. A ceramic switch 

and an Amphenol S0239 connector have 

been mounted on a bracket attached to the 

backing plate. The two capacitors have been 

connected from the switch to ground, 

leaving one position a direct connection with 

no capacitanbe added. In this way it is a 

simple matter to hop out of the car, change 

the coil and tip, and merely turn the switch 

to the position required for the given 

antenna. My thanks to Bill for the actual 

construction. 

...W1EMV" 



96 



73 MAGAZINE 







An amateur I contacted the other day 
said he was using a 10 meter dipole for 20 
meters and was getting an swr of I -2:1 
—which is hard to believe. He said his "swr 
is low and the transmitter loads up' 1 and 
therefore he was perfectly happy with this 
arrangement. However, on 40 and 80 meters, 
he could not use this 10 meter dipole since 
the swr was greater than 8:1. 

The idea of a two-band dipole intrigued 
me, so I pressed for more details. He was 
using 200 ft of RG-58/U coax and a 1 kW 
amplifier. The weather was cold (New 
England winter), lie was getting out, and 
therefore he was not about to change this 
arrangement. 

His transmission line was acting as a "loss 
pad/* an impedance matching scheme which 
is used extensively in audio work. A loss pad 
can take the form of a T, H, ladder, or even 
a simple series resistor. Its gain is always less 
than unity- 
Consider the simple case of a 5 kfl plate 
load to be matched to a 10S2 voice coiL A 

m 

perfect match results if a 4,99 kf2 resistor 
were put in series with the 1012 voice coil. 
But look what happens to the useful power 
output. Approximately 1/500 of the power 
appears across the voice coil and the rest is 
lost as joule heat in the resistor. 

This also reminds me of two experiments 
which I developed for lecture demonstra- 
tions. In one experiment I load up a pair of 
oldfashioned bedsprings connected back-to- 
back in dipole fashion, gamma matched, to 
perfect swr. The transmitter loads up but 
there is little radiation. 

The other experiment uses 225 ft of 
RG-8/U coaxial line of mongrel origin which 
shows good swr but blisters badly when 1 
kW is pumped into it. 

- . . Katashi Nose KH6IJ/1 ■ 



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FEBRUARY 1970 



97 



Getting Your Extra 

Class License 



STAFF 



Part XIII: Examining 

Filtering and RTTY 



In the beginning, ham radio had only one 
kind of communication available -tele- 
graphy, using a hand key. (We can't call it 
CW> because in those days continuous-wave 
transmissions didn't exist; spark gaps gener- 
ated the rf.) 

As the years passed, the spark gave way 
to CW, and telegraphy gave way to voice 
communications to some degree. Voice work 
was all done with AM originally, but as the 
art progressed FM and the many varieties of 
sideband joined the procession. 

Today, ham radio has its choice of many 
kinds of communication techniques. Hand- 
key CW, automatic-key CW, AM voice, FM 
voice, SSB, and DSB are the most widely 
used, but facsimile, television, and digital 
telegraphy (more commonly known as 
RTTY) are also very much in the picture. 

Since the Extra Class license is the highest 
grade issued in the Amateur Radio Service, 
the FCC rightfully insists that aspirants to 
this ticket be famiiiar with the entire range 
of techniques available to hams. As a result, 
the examination for the Extra Class license 
includes questions on the lesser-used 
techniques as well as on the more common 
practices. 

In this section of our study course, weTl 
look at some of these more specialized 
questions. Specifically, we'll cover the 
subjects of RTTY and filtering. On the 
official study list, these subjects are the basis 
of the following questions: 

5, What is meant by "frequency shift 
keying'* and how is it accomplished? 



13. Draw a block diagram of an RTTY 
system showing the primary function of each 
stage. What is the proper way of identifying 
an RTTY transmission? What is the most 
widely used frequency difference between 
the mark and space frequencies in a conven- 
tional RTTY transmitter? 

41. How do filters attenuate harmonic 
emissions? 

49. If a crystal lattice filter has band- 
widths of 3 kc/s at the 60 dB points and 1,5 
kc/s at the 6 dB points, calculate the shape 
factor. At what frequency is the best shape 
factor achieved in a crystal lattice filter? 

64, How do phasing condensers help 

stabilize crystal filter circuits? 

Following our usual practice, we'll sup- 
plant these highly specific questions with a 
set of more general questions for our discus- 
sion. This time, we will actually have two 
sets, one for each of our two subjects. 

The starting point for RTTY is most 
generai~"What is RTTY?" Filling out this 
subject is our second question, "How is 
RTTY transmitted and received?** 

On the subject of filters, we must be 
almost as general and begin by asking, "How 
do filters operate?" We can then ask ? "How 
is filter performance rated?" and finally 
become a bit more specific when we 
examine "How are rf bandpass filters con- 
structed?" 
Radio tele type 

What h RTTY? The first electrical 
communications technique was, of course, 
telegraphy. Samuel F, B. Morse is generally 



93 



73 MAGAZINE 




credited with the invention of telegraphy 
(although, like Marconi in the case of radio, 
Morse's major contribution was to gather a 
number of discoveries made by others into a 
working system and promote it to the 
world). The familiar hand key was, for 
several decades, the only means of origin- 
ating any electrical communication. 

As the years passed, a number of inven- 
tors attacked the problems imposed by the 
hand key and its requirement for an oper- 
ator who knew the telegraphic code. Eventu- 
ally, Joy Morton and Charles L Krum 
developed a machine which was able to 
bypass the operator requirements. It was, 
essentially, a cross between a typewriter and 
a telegraph system. In 1915, the Associated 
Press adopted the Morkrum machine. 

Meanwhile, Edward Kleinschmidt 
independently came up with a machine to 
perform the same purpose. In 1925, the 
Morkrum and Kleinschmidt companies 
merged, and five years later AT&T bought 
the firm. The machine was named "Tele- 
type" by blending the prefixes of "tele- 
graph" and "typewriter," and the firm was 
named the Teletype Corporation. The word 
'Teletype" is, incidentally, still a registered 
trademark of the Teletype Corporation and 
cannot legally be used to refer to any other 
make of teleprinter equipment. Its common 
abbreviation, "TTY," is not a trademark and 
can be used as a general term. 

TTY machines were designed with the 
requirements of land-line telegraphy in 
mind, but during World War II it became 
apparent that radio transmission could 
replace the land-lines with little change in 
techniques-and RTTY (radio TTY) was 
born. 

Amateur RTTY got its start in 1946 
when a number of hams on both coasts, in 
a parallel but apparently unconnected action, 
persuaded several companies to release 
obsolete machines to ham use instead of 
smashing them for junk. 

Today, TTY equipment has many uses 
besides the original land-line telegraphic 
application, and as a result machines are not 
too difficult to locate. For instance, TTY 
equipment is widely used in the digital 
computer industry (where the machine is 
known as a "remote terminal") and as of the 



summer of 1969, at least a dozen firms were 
producing machines for this purpose which 
had never participated in the telegraph- 
communications use. 

The principle upon which TTY operates 
is similar to that of normal CW transmission, 
with one major difference. Where CW makes 
use of five different kinds of signals-dits, 
dahs, and three lengths of spaces to indicate 
in-the-character space, word space, and 
sentence space— TTY uses only two. The two 
kinds of signals used by TTY are called 
"mark" and "space" and may be represented 
in several different ways. The advantage 
gained by using only two kinds of signals is 
that a machine can then interpret the signal 
with a minimum of "logic" or decision- 
making circuits; conventional CW with its 
one-unit dit, three-unit dah, and one-, three-, 
and five-unit spaces would require much 
more interpretation to decode. This is simple 
for humans, but most complicated for a 
machine to perform (although machines 
have been built to do so). 

Because of the differences in the kinds of 
signals used, TTY equipment does not 
employ the International Morse Code. 
Instead, it uses one of several other codes 
which assign characters to combinations of 
the mark and space signals. Amateur and 
most commercial equipment uses the "Inter- 
national Five-Unit Code," but equipment 
designed for use with computers is more 
likely to employ the "American Standard 
Code for Interchange of Information*' or a 
different code originally introduced by the 
Friden Company for its "Flexowriter" equip- 
ment. 

Regardless of the code used, the signals 
sent and received by a TTY machine consist 
of groupings of "mark" and "space" signals. 
At the machine itself, "mark" is usually 
represented by the presence of current in the 
line, and "space" by the absence of current, 
so that they can be thought of as "on" and 
"off" conditions. This same representation 
can be used in the circuit from one machine 
to another, and the result is known as "make 
and break keying," Ordinary CW is sent by 
make and break keying, for instance. For the 
machines, however, the use of make and 
break keying makes it impossible to dis- 
tinguish an extended "space" condition 



FEBRUARY 1970 



99 



" 




from a circuit failure and resulting total loss 
of signal— and so other representations are 
usually employed instead. 

The most common technique used to 
represent "mark" and "space" conditions in 
RTTY is to use two radio frequencies rather 
than just one. One frequency represents 
"mark" and the other is "space." Now a loss 
of signal can be recognized by the absence of 
both the mark and the space signals, while 
an extended "space" condition is signaled 
by the presence of the space signal. 

The two frequencies are usually very 
close together. The difference between the 
mark frequency and the space frequency is 
known as the "shift," and the normal shift is 
only 850 Hz. This tends to minimize 
fading because the two signals will fade 
together. Narrow-shift is also used, with a 
shift of as little as 150 Hz, to minimize 
fading effects still more. Any shift less than 
900 Hz is legal for use. 

It makes no difference which of the two 
frequencies is used for "mark" and which 
for "space/ 1 but common ham practice is to 
use the higher of the two frequencies for 
"mark." In case one station chooses to 
reverse this, all the other station need do is 
to reverse the polarity in his receiver— which 
may be done by merely tuning to the other 
side of zero beat. The situation is exactly the 
same as the choice between upper and lower 
sidebands in SSB operation. 

In TTY work, again regardless of the 
actual code used (and for the rest of our 
discussion we will assume that the Inter- 
national Five-Unit Code is the one to be 
used, since it is the one required for ham 
RTTY by FCC regulations), each character 
begins with a "start" signal and ends with a 
"stop" signal. This makes the total character 
length with a five-unit code actually seven 
units, 

The "start" signal is always a "space" and 
the "stop" is always a "mark*" These two 
signals establish timing synchronization 
between the transmitting machine and the 
receiving machine, and thus make it possible 
for the intervening code signals to be 
decoded. 

When no character is being transmitted, a 
steady "mark" signal is sent. The "space" 
condition produced by the start portion of a 



character then starts the machine's decoding 
mechanism. The decoding mechanism sorts 
out the next five signal conditions to deter- 
mine what character is being sent, and stops. 
The "stop" portion of the character simply 
provides enoughl time for the decoder to 
come to rest before another character can be 
sent. 

Normal speed for amateur RTTY equip- 
ment is 60 wpm. At this speed, each part of 
a single character (except for the "stop") 
lasts for 12 milliseconds. The stop is half 
again longer, or 31 msec, for a total char- 
acter duration of 163 msec. 

A TTY machine has the appearance of a 
typewriter; its major parts so far as the 
operator is concerned are the keyboard and 
the printer, 

When a key on the keyboard is pressed, it 
sets up in some type of memory device the 
actual code to be transmitted. This memory 
device may be either mechanical or elec- 
tronic. The machines in general use all 
employ mechanical memory; pressing a key 
pushes down a notched lever, which then 
latches in the "down" position. Each key 
has a different lever, and the notches on 
each lever correspond to the "space" por- 
tions of the character for that key. All these 
notched levers rest on top of and across 
another set of five levers, so that when a 
notched lever is latched down it pushes 
down any of the second group of levers 
which do not have notches above them, and 
leaves up any of the second group which are 
matched by notches. 

This second group of levers operates a set 
of five contacts, one for each unit of the 
character code, A motor-driven distributor 
then wipes a selector brush across the five 
contacts in turn (the "start" bit of the 
character is built into the selector mechan- 
ism, as is the "stop" bit at the end). If the 
contact lever for any one unit is up, a 
"space" is sent when the selector brush 
wipes across that contact; if the contact 
lever is down, a "mark" is sent. When the 
selector brush leaves the last contact, the 
distributor motor stops and the keyboard is 
unlatched in preparation for the next charac- 
ter to be sent. 

Figure I shows the international 5-unit 
code, without start and stop bits. The 



100 



73 MAGAZINE 






CH 
LTR 


AR. 
FIG 


c 

1 


2| 


DE 

f 


E 

3 


JIT 
4 


s 

5 


A 


" i 


i 

X 


X 











B 


? 

■ 


X 




o 




X 


X 


C 


- 




X 


o 


X 


X 




D 


$ 


X 




o 




X 





E 


3 


X 




o 






F 


t 


X 




o 


X 


X 




G 


& 




X 


o 




X 


X 


H 


lbs 






o 


X 




X 


1 


8 




X 


o 


X 






J 


i 


X 


X 







X 




K 


( 


X 


X 


o 


X 


X 


■J 


L 


) 




X 


o 






X 


M 








o 


X 


X 


X 


N 


t 


1 


' 


o 


X 


X 







9 






o 




X 


X 


P 







X 


o 


X 




X 


Q 


1 


X 


X 


o 


X 




X , 


R 


4 




X 


o 




X 




S 


bel 


X 







X 






T 


5 






o 






X 


U 


7 


X 


X 


o 


X 






V 


■ 




X 


o 


X 


X 


X 


w 


2 


X 


X 


o 






X 


X 


_,/ 


X 




o 


X 


X 


X 

X | 


z 


tt 


X 




o 






space 






o 


X 






car ret 






X 




X 




line fd 




X 


o 




. 




f'9 


X 


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o 




X 


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Itr 


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X 


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1 

X 


X 



Fig. 1, International 5-Unit Teleprinter 
Code, required by FCC regulations for use 
in ham TTY. "x" entries represent "mark" 
pulses and blank entries represent "space" 
pulses. See Fig. 2 for timing of signal and 
start-stop frame which surrounds each char- 
acter code. 

column headed "code bits" shows the code 
as it would be represented on paper tape; bit 
1 is the first one sent after the start bit, and 
bit 5 is the last sent The "f" column with its 
all-"o" entries represents the sprocket feed 
hole of the punched paper tape, and is not a 
part of the code. An "x" in any entry 
represents a "mark" condition, and a blank 
represents a "space." 

We have seen how the operator's pressure 
on any one key is translated into the code 
pattern to be transmitted to represent that 
character. The reverse operation, translation 
of a received code pattern into a character to 
be printed, is accomplished in much the 
same way by the printer. However, the 
printers of the various models of TTY 
machines are the areas in which the most 
drastic differences occur. 

The explanation of printer action which 
follows is based on the action of the 
Teletype Model 12 machine, which is now 



obsolete. More recent machines operate in 
substantially different ways, but the model 
12's operation serves to explain the basic 
idea without complicating the description 
with the complexities of single-magnet oper- 
ation. 

The received signal is applied to the 
printer as a make-and-break keyed current, 
with "mark" represented by the presence of 
current and "space" represented by its 
absence. Fn the absence of any received 
signal, "mark" condition exists and current 
is flowing through the printer line. 

In the printer, this current flows through 
a latch relay and six selector magnets. So 
long as current flows through the latch relay, 
the printer is inactive. 

When a character appears, its arrival is 
indicated by its "start" bit which is a 
"space" condition. This drops out the latch 
relay and permits the drive motor to turn 
the receiving distributor through one revolu- 
tion. 

As the receiving distributor rotates, it 

connects each of the six selector magnets, in 
turn, to the signal line at 22 msec intervals. 
Each selector magnet is either tripped or 
unaffected by the signal line; if the line 
condition is "mark" when the selector is 
connected to the line, the magnet is tripped, 
and if the line condition is "space" nothing 
happens. 

The first five selector magnets control 
notched levers, which in the "tripped" 
position block movement of the key levers 
which do the actual printing. When all five 
of these notched levers have been tripped, 
only one key lever can match the notches in 
all of them. Every other key lever wiJl fail to 
match a notch in at least one of the code 
levers; 

The sixth selector magnet, which is 
tripped by the stop bit, permits the printer 
motor to drive the key-lever mechanism and 
print the one character which matches. After 
the printing, the entire mechanism is reset to 
its initial conditions and the receiving dis- 
tributor stops, ready to start again which the 
next start bit arrives. 

In later machines, only a single selector 
magnet is used and its mechanical action is 
routed to the appropriate points for each bit 
by a cam which sets up toggle action at the 



FEBRUARY 1970 



101 



H a ~K 



-H"— I- 



wvm 



SPACE 



START 



BIT 



QiTt | BJT2 | BIT 3 | BIT 4 | QJt 5 j STOP 



CHARACTER 
(163 



Fig, 2, This waveform shows the appearance 
of the character "B" as transmitted in the 
asynchronous serial BTTY code. While code 
contains only five units, character as sent 
includes seven. Every character has a 

'space" start unit, and a "mark" stop unit, 
in addition to the five units which carry 
character's meaning. All bits except stop bit 
are equal length, 22 msec at 60 wpm speed. 
Stop bit is longer, 31 msec at 60 wpm, to 

'pad out" to transmission rate and allow 
time for equipment to stop between char- 
acters. 



proper time. Some machines do not use key 
levers; instead, they position a "type box" in 
front of a hammer so that the selected 
character will be printed when the hammer 
strikes. 

Not all characters in a TTY machine 
cause printing. Some, such as "carriage 
return/' "line feed/' •letters," and "fig- 
ures" cause mechanical action in the printer 
instead, 

What we've looked at so far in this 
examination of RTTY principles is simply 
the keyboard and printer portions of the 
TTY machine itself, and applies equally to 
land-line or wireless operation, 

In a land-line setup (called a "local loop" 
when one is set up in a ham shack, as for test 
purposes), the keyboard contacts are con- 
nected in series with the printer selector 
magnets and a power supply which fre- 
quently is 150V dc at 20 or 60 mA. Pressing 
a key causes generation of the code char- 
acter, and the serial code character operates 
the selector magnets and causes the printer 
to print. If this all happens in the same 
machine the result is an electric typewriter; 
if the keyboard and printer are in different 
machines, the result is telegraphy without 
Morse code. 

To convert the telegraphy setup to radio, 
all we need do is find some way to put the 
"mark" and 
rather than on copper wires, and then 
recover it to drive the printer. 



"space" information on rf 



We could simply substitute the keyboard 
for the hand key in a CW installation, and 
we would have make-and-break keying, The 
first amateur work over long distances was 
done in this manner because no other form 
of teletype operation was permitted by the 
FCC. At the receiver, the audio was con- 
verted to dc current to drive the selector 
magnet and that was all it took. 

However, make-and-break is no longer 
used in RTTY. Frequency shift keying 
(FSK) is almost universally used. The fre- 
quency shifted may be the carrier itself 
(FSK), or an audio frequency modulated 
upon the carrier (AFSK). FSK is used in the 
HF bands, but AFSK is used by VHF RTTY 
enthusiasts because of the difficulty in 
controlling small shifts at high frequency, 

A typical RTTY station is shown in block 
diagram form in Fig. 3, and compared to an 
AM station. You can see that the major 
differences lie in the TTY machine itself, 
and the circuits connecting it to the trans- 
mitter and the receiver. 

The transmitter and receiver themselves 
serve the same purposes as in any other radio 
communications system. The TTY machine's 
keyboard generates the proper code for the 
character to be sent, and the "TTY modula- 
tor" converts this code into the proper 
modulation for the transmitter (frequency 
shift or FM for FSK, and a shifting audio 
frequency plus audio modulator circuits for 
AFSK), The "converter" or "terminal unit" 



V 



•— RCVR 



TERMINAL 

UNIT 



PRINTER 





-** MACHINE 






i 


KEYBOARD 




TTY 
MODULATOR 






L_ 


KMTR 










Fig* 3, Block diagram of typical RTTY 
station. AM station would be same except 
that speaker would replace terminal unit 
and printer at receiver output, and micro- 
phone would replace keyboard, together 
with AM or FM modulator or sideband 
generator replacing TTY modulator, at 
transmitter input. Major difference is 
presence of TTY machine, and addition of 
TU and TTY modulator to interface with it. 



102 



73 MAGAZINE 



converts the receiver^ output into a make- 

and-break-keyed current suitable for the 

TTY machine's printer, and the printer then 

converts this intermittent current flow into a 

character image on paper. 

In the early days, amateur RTTY stations 

were required to identify themselves by 

ordinary CW at 10-minute intervals, as well 

as identifying in the TTY transmission. 

Rules have since been modified to permit all 

identification to be done in TTY, The 

general requirements for identification are 

the same as for all other amateur stations; 

both the transmitting station and the 

receiving station must be identified by call 

sign. 

How is RTTY Transmitted and Received? 

WeVe already examined the means by which 
the operator's pressure on any one key of 
the keyboard is converted into an electrical 
code representing the chosen character, and 
the received electrical code is converted back 
into a printed representation of the char- 
acter. But what goes between? 

Of course, a radio transmitter and a 
receiver are used, but the TTY modulator 
and the converter or terminal unit are the 
items we're most interested in at this point. 

There are almost as many different TTY 
modulator circuits and terminal unit designs 
as there are RTTY enthusiasts, but most of 
these different designs have many items in 
common. 

The major differences, in fact, are 
brought about by the choice of FSK or 
AFSK for the modulating technique, and by 
the choice between FM discrimination and 
simulated make-and-break for the terminal 
unit. 

If FSK is to be used* the TTY modulator 
must vary the frequency of the transmitter, 
and the terminal unit may either generate 
the driving signal to the printer directly from 
the receiver's i-f, or indirectly from audio 
tones produced by the bfo. 

If AFSK is to be used, the TTY modula- 
tor must first provide a frequency-shifting 
audio tone and then modulate the trans- 
mitter with this tone. Except for the keyed 
audio oscillator, normal AM transmitter 
techniques are usually used. The terminal 
unit for FSK must be of the audio variety. 

Since an audio terminal unit can be 



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FEBRUARY 1970 



103 



employed for either AFSK or FSK operation, 
most of the popular designs have been based 
on this principle. For FSK-only use, however, 
the straight FM technique can provide the 
ability to dig much deeper into the crud and 
noise of a crowded band for solid copy of a 
weak signal. 

Let's examine at least one of each of 
these types of equipment to see how it 
functions, Since RTTY in amateur radio 
began with AFSK, we'll examine an AFSK 
modulator and terminal unit first, followed 
by the FSK equipment. 

One of the most popular RTTY terminal 
units ever described was that designed by 
Marvin Berstein, W2PAT, and originally 
published in QST. The W2PAT unit provided 
an introduction to RTTY for a majority of 
the pioneer RTTY enthusiasts— and more to 
our point, is an excellent example of a 
complete AFSK unit. It included both the 
oscillator to provide a keyed audio tone to a 
conventional AM transmitter, and the 
receiving converter to turn received tones 
into serial character codes to operate the 
printer. 

The AFSK oscillator (Fig. 4) is almost 
completely conventional The Hartley circuit 
provides a stable sine wave output with a 
minimum of components, but any other 
oscillator circuit could have been used (and 
most other circuits were, in one or another 
of the various designs which followed). The 
part which makes this circuit different from 
an ordinary oscillator is the diode switch and 
frequency-shift capacitor circuit, consisting 
of resistor Rl, diodes Dl and D2, and 
capacitor C2, 



005 



+ 250 




XMTR 



Fig. 4, AFSK oscillator from W2PAT- 
designed installation. Inductor is TV width 
coil. Output of this oscillator feeds conven- 
tional AM transmitter's mike jack. Capacitor 
C2's value is varied to adjust for proper 
shift. 



AFSK operators normally indicate 
"mark" condition with a tone of 2125 Hz, 
and "space" with a tone of 2975 Hz. The 
oscillator is tuned, by adjustment of the coil 
inductance and the value of capacitor CI, to 
produce output at 2975 Hz when the keying 
circuit is open-circuited* 

When the keying circuit is closed, Rl is 
shorted out. This permits diodes Dl and D2 
to switch capacitor C2 into the circuit in 
parallel with CI, thus lowering the output 
frequency. The value of C2 is adjusted by 
trial and error until the output frequency is 
2125 Hz. 

Operation of this diode switch may 
appear a trifle mysterious at first, since no 
external power is supplied to turn the diodes 
either "on" or "off." What actually happens 
is that the diodes rob enough power from 
the oscillator tank circuit to develop their 
own switching voltages. D2 conducts for half 
of each cycle regardless of the keyboard 
contact position; during the half-cycle that 
D2 is "off/ Dl attempts to conduct. The 
current flow through Dl, however, must 
flow through Rl, and a voltage is developed 
at the "hot" end of Rl which tends to keep 
C2 isolated from ground. 

When the keyboard contacts are closed, 
Rl is no longer in the circuit and the current 
flow is direct to ground on both halves of 
the audio cycle (through D2 on one half and 
Dl on the other). The diodes now act just 
like a closed switch, and cut C2 into the 
circuit. 

Because of the diodes, the keyboard 
contacts handle only a small amount of 
dc rather than being required to switch 
ac or high-current dc. This minimizes rf 
interference to the receiver-in RTTY this is 
an important point, because the printing 
action on the machine normally results from 
the signals which have gone all the way 
through the system, rather than on any 
direct connection between keyboard and 
printer. 

The receiving-converter portion of the 
W2PAT terminal unit (Fig. 5) is not so 
familiar-looking as the oscillator. It consists 
of a double-diode limiter followed by a 
two-stage amplifier which is operated in an 
over-driven condition to serve an additional 
limiting function. Output of the active 



104 



73 MAGAZINE 




LIMITER 

6SL7 
U2AX71 



RELAt DRIVER 

fiSNT 

(I2AU?) 



IN PUT j»* 




+250 



Fig. 5. Receiving-converter portion of 
W2PAT design, less power supply. See text 
for discussion of operation. Neon tubes at 
Jower center of diagram are type NE-54. 
Inductors in filters are TV width coils. 



limiter is then applied to the detector 
circuit, and detector output drives the final 
current amplifier. The current amplifier 
operates a relay, and the relay contacts drive 
the printer selector magnets. 

The active limiter provides an output 
level of 15V, ±1 dB, with input signals 
varying over the range of 450 mV to 
more than 30V. This 15 V signal is 
applied to the detector, which actually 
consists of two separate grid-leak detectors, 
each tuned to a separate audio frequency. 
One half of the circuit is tuned to the mark 
frequency and the other half to the space 
frequency. Since only one of these two 
frequencies is present at any one time, one 
side of the circuit is always drawing more 
current than is the other side, and this swing 
of the heavy current flow from one side to 
the other in the detector stage corresponds 
to the markor-space condition of the TTY 
signal. 

The plates of the two detector circuits are 
coupled through neon bulbs to the grids of 
another dual-triode tube. The neon bulbs act 
as threshold devices. Until firing voltage for 
the neon is reached, grid voltage on the final 
tube remains zero. When current flow in one 
side of the detector drops due to lack of 
signal at the associated frequency, the plate 
voltage rises, and when the neon fires the 
grid of that side of the current amplifier 
tube goes positive. This makes that half of 
the final tube draw heavy current, thus 
pulling the polar relay to the corresponding 
position. 



rti 



POLAR 
RELAY 




PRINTER 



<►— Wv 



05 



2 2M 

©NE-54 /^T\NE-M 

DETECTOR ( -^W 



/77 



2 ZU 




(IEAXT) 







oos 



When the AFSK signal's frequency 
returns to that to which the detector is 
tuned, the detector stage current increases 
and plate voltage drops. When plate voltage 
falls below about 55V, the neon goes out 
and the grid of that side of the current 
amplifier returns to ground voltage. At the 
same time, plate voltage in the other half of 
the detector was rising and turning on the 
other side of the current amplifier thus 
reversing current through the output relay 
and driving it to its other position. 

The milliammeter connected between the 
plates of the current amplifier stage is a 
tuning indicator. When tuned to a TTY 
signal which has a mark-to-space ratio of 1 : 1 
(as much time spent in mark condition as in 
space condition), the meter will indicate 
zero average current. This is because the 
meter movement is unable to follow the 
rapid fluctuations of current, and if the 
mark-to-space ratio is 1 : 1 , the average current 

fluctuation will be zero. 

Another way to provide such a test signal 

is simply to key an AFSK oscillator with a 

square wave or an electronic key set for all 

dits; the RYRYRY sequence is traditional 



FEBRUARY 1970 



105 



but the keyed oscillator is more reliable 
since it does not depend upon the keyboard 
being in proper adjustment. 

Many other AFSK units have been des- 
cribed and put into use since the W2PAT 
unit made its appearance; a large portion of 
those in use today use transistors rather than 
tubes. The basic principles of all are similar, 
however, in that the two audio tones are 
split into separate channels and the TTY 
code is recovered by detection of both 
channels. The Jimiter is also a usual feature 
since it provides the ability to operate with a 
minimum of critical receiver adjustment 
between stations. 

FSK equipment is similar in many ways 
to AFSK gear, but differs in some important 
respects. The modulator consists of a circuit 
to switch capacitance across the tuning 
circuit of the regular transmitter vfo (crystal 
oscillators are difficult to get enough shift 
on). Such a circuit is shown in Fig. 6. Like 
the AFSK oscillator, a diode switch is used, 
but this diode switch is powered by voltage 
stolen from the transmitter B+ supply. The 
function of the switch is to connect the 
added capacitor CI across the tuning capaci- 
tor when the keyboard contacts are open* 
and to remove it when the contacts are 
closed. This makes "mark" the lower fre- 
quency and "space" the higher one. Note 
that this is the exact reverse of AFSK 
practice. 

The frequency shift is usually 850 Hz, 
but any shift less than c >00 Hz can be used 
legally. The variable resistor controls the 



+ ao 




Fig. 6. Typical switching circuit for direct 
FSK. 3*30 pf trimmer is coarse adjustment 
on maximum amount of shift attainable; 1 
meg pot is operating adjustment. All com- 
ponents to right of rf choke should be 
mounted as close as possible to vfo tank 
circuit, and be made mechanically soNd to 
avoid frequency instability. Components to 
left of rf choke may be located anywhere. 
Keyboard contacts must be insulated from 
ground for use in this circuit. 



amount of shift, by varying the effect of the 
added capacitor. When changing from one 
band to another, this resistor normally must 
be adjusted to take into account the fre- 
quency multiplication introduced by most 
transmitters at the higher bands. 

Many RTTY enthusiasts receive FSK by 
using AFSK terminal units, converting the 
FSK signal to AFSK by turning on the 
receiver bfo and tuning carefully. 

However, an FSK signal is an FM signal, 
and an FM detector operating at the re- 
ceiver's intermediate frequency can in many 
cases give superior performance. The FM 
detector can be any of the conventional FM 
detector circuits— discriminator, ratio detec- 
tor, or pulse counter. Its major point of 
difference from audio AM detectors is that it 
must respond to low-frequency signals, since 
the 22 msec duration of a TTY bit is about 
23 Hz in sine-wave terms. 



LIMIT t" 

ILAST r 

STAGE) 



DIS- 
CRWINATQW 

(RATIO DET- 
ECTOR! 



CATHODC 
FOLLOWER 



- — 

MAGN£T 




DRIVER 




1 




SEL 






MAG 

IN 










TTT 







-& 



Fig. 7, Block diagram of typical direct-FSK 
or if RTTY terminal unit. Limiter and FM 
detector are completely conventional, but 
from FM detector output all the way 
through to TTY printer selector magnets dc 
coupling is employed. 



Such a direct-FSK terminal unit is shown 
in block-diagram form in Fig. 7. Both the 
limiter and discriminator stages are com- 
pletely conventional. The cathode follower 
between the discriminator and the driver 
stage permits direct coupling for good low- 
frequency response. 

The driver stage is a switching circuit, so 
hooked up that a "mark" signal produces 
current flow through the output terminals 
and a "space" signal stops the flow of 
current. Both positive and negative power 
supplies are used so that the output ter- 
minals will be at approximately ground 
potential to minimize shock hazards. 



106 



73 MAGAZINE 



Filtering Devices 

How Do Fitters Operate? The temptation 

is always present to answer a question 
phrased "How do . . ♦ " with "Very well, 
thank you!" and let it go at that— but this 
would hardly be fair, since we asked the 
question ourselves in the first place. Besides. 
many filters operate only poorly, if at all, 
because until very recently filter design was 
essentially a cut-and-try proposition. Clas- 
sical theory upon which the design was 
based called for physically impossible com- 
ponents in the filter, and substitution of 
realizable items led to inaccuracies in the 
design. This situation, fortunately, has now 
been cured, and well look at "how" a little 
later. 

The purpose of a filter is to separate ac 
signals. In general, a filter must fall into one 
of four categofies— * 'high pass," k 'low pass," 
"bandpass," or "bandstop." A highpass filter 
passes all signals higher in frequency than its 
cutoff frequency and stops all lower- 
frequency signals. A lowpass filter does the 
reverse. A bandpass filter passes all signals 
between its lower and upper cutoff frequen- 
cies and blocks signals either higher or lower 
in frequency than its passband limits, and a 
bandstop filter blocks passage of frequencies 
within its band while permitting all others to 
pass. 

These four categories of filters are based 
upon the action performed by the filter. 
Any filter, though, must operate at some 
specific frequency or frequencies. The fre- 
quencies involved may be subsonic, audio, 
intermediate, or radio frequencies. The 
design of any specific filter depends upon 
both the action to be performed, and the 
operating frequencies involved. Components 
employed in the filter, and the apparent 
principle of operation, may vary widely with 
the action and the frequency. 

However, when we get right down to the 
basics we find that all filters operate on the 
same basic principles despite apparent dif- 
ferences. These apparent differences are best 
illustrated by some examples of various 
filters: The filter portion of a power supply 
is a lowpass filter operating in the subsonic 
frequency range, while the TV1 filter on a 
transmitter output is usually a lowpass filter 
operating in the rf region. A TVI filter of the 
sort connected to affected TV receivers is a 



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FEBRUARY 1970 



107 




highpass filter operating in the rf range. The 
mechanical filter used in SSB work is a 
bandpass filter operating at the intermediate 
frequency, and so are the crystal lattice 
filters also used in SSB. For that matter, an 
i-f transformer is a bandpass filter, as is any 
resonant circuit. RTTY filters are also band- 
pass designs, but operate in the af region. 

All filters are based on the frequency- 
dependent properties of reactances (even the 
mechanical filter makes use of the mechan- 
ical equivalent of electrical reactance). 
Capacitive reactance X c decreases as signal 
frequency / rises, while inductive reactance 
Xj goes up with increasing frequency, By 
proper choice of the type and amount of 
reactance any desired filter action can be 
obtained (within reasonable limits, as we 
shall see a little later). 

To illustrate the principle, let's examine a 
single stage, subsonic, lowpass filter typical 
of those used in many power-supply designs. 
The schematic appears in Fig. 8. 

L 



m 



T 

X 



./"v^rvx 



CUT 



Fig. S. Single section lowpass filter. Values 

of L and C determine cutoff frequency of 
fiHer section. 

At frequencies far below the "cutoff 
frequency of this stage, the inductor pre- 
sents a very low value of Xf and the 

capacitor has a very high value of X c > Both 

reactances are so extreme that they may be 
ignored, and the filter becomes in effect a 

straight piece of wire with no effect on the 

signal. 

At frequencies far above cutoff, the 
situation reverses. The inductor's reactance 
is very great and the capacitor's reactance is 
very low. The filter becomes in effect a dead 
short, with no path from input to output, 
and the signal is blocked. 

The "cutoff" frequency of this type of 
filter is defined as being that frequency at 

which Xj equals X c . At this frequency, since 
reactance is equal in both directions, half the 
signal current flows to ground and the other 
half flows through the filter. The signal is 
neither passed without loss nor blocked 
completely. 



At frequencies near cutoff, the situation 
is similar to that at the cutoff frequency, 
Signals slightly below cutoff frequency will 
be slightly attenuated, but the lower the 
frequency becomes the more of the signal 
goes through and the less of the signal is 
bypassed to ground. Signals slightly above 
cutoff are still partially passed, but as the 
frequency rises less and less of the signal 
makes it through the filter. There is no such 
thing as a perfect filter which passes every- 
thing below cutoff and blocks all above. 

Filter performance can be improved, 
though, by adding more stages. If two of 
these stages are cascaded one after the other, 
then at cutoff frequency the first stage will 
block half the signal and permit half to pass. 
The second stage will block half of the half 
that passes through the first, and permit 
only 1 /4 of the original signal to get through 
the composite filter. 

Adding a third such stage will reduce the 
output signal level to 1 /8 that at the input, 
A fourth stage will halve this, to 1/16 the 
original level. Five stages will cut the output 
to 1/32, and so forth. 

When extra stages are added, though, the 
definition of "cutoff frequency" must be 
changed. Each stage's cutoff frequency is 
defined exactly as before, but the cutoff 
frequency of the filter as a composite unit 
becomes lower with each added stage* 
because for any filter the definition of 
"cutoff frequency 1 " most generally used is 
that frequency at which the filter reduces 
output signal level to half the level present at 
the input. 

Our two-stage filter in the example would 
have a composite cutoff frequency only 
0.7071 times as great as the single-stage 
filter: the three-stage filters cutoff would be 
at a frequency half that of the single stage 
filter. These ratios apply only to the simple 
design shown in Fig, 8; more complex filter 
designs have different rates of cutoff- 
frequency change, and in general a filter is 
designed for specified performance rather 
than being built up of some arbitrary 
number of identical stages. 

We have just examined the basic prin- 
ciples as applied to a simple lowpass filter. 
A highpass filter works the same, except 
that the inductor and capacitor are inter- 



108 



73 MAGAZINE 



changed so that signals above cutoff are 
passed and those below cutoff are blocked 
rather than vice versa as in the lowpass 
circuit. 

To get a bandpass filter, we could simply 
build a highpass filter with cutoff set at the 
lower band limit, and follow it by a lowpass 
filter with cutoff set at the upper band limit. 
For extremely wide passbands this is some- 
times done. One example is the 300-3000 
Hz band frequently used for voice com- 
munication; this is too wide a bandpass for 
simple bandpass filters to handle, and the 
economical way out of the problem is to 
first trim off one limit and then trim the 
other. 

For narrow passbands, though, something 
more like a tuned circuit is generally used. 

Not all filter stages are as simple as that 
shown in Fig, 8, Tuned circuits may be 
included instead of simple reactances, and 
the resonance frequencies may be far dif- 
ferent from the intended cutoff frequency in 
order to modify filter performance. The 
variations possible in filter design on this 
basis gave rise to the "image-parameter" 
theory of filter design, which ruled the 
design of most filters for more than 30 years 
and even today is still widely used. 

However, reactances which satisfy the 
demands of image-parameter theory are 
physically impossible, because the theory 
demands that the resistive portion of the 
circuit be zero at cutoff frequency, changing 
in the same manner as a capacitive reactance 
below cutoff, and changing in the same 
manner as an inductive reactance above 
cutoff, while actual resistances are indepen- 
dent of frequency. 

Because many filter requirements are 
only approximate, this design method has 
been able to give circuits acceptable for most 
purposes. When more accurate designs were 
required, cut-and-try fitting of values was 
the normal course. 

Any filter, though, is a network of 
components connected together, and any 
such electrical network must obey certain 
basic rules known to engineers as "Kirchoff s 

Laws." These state, in essence, that as much 
current must flow into any point as flows 
out and vice versa. We might say simply that 
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109 



■ 



These rules can be written as a series of 
algebraic equations, and to apply them to 
the analysis of any arbitrary network we 
must do just that The laws state that all the 
current must be accounted for, and the 
equations do the accounting. 

Since a filter is a network, the filter can 
be described by a suitable series of equa- 
tions. The filter designer can then solve the 
equations to find the network parameters 
which will produce optimum performance in 
some desired respect. Performance will be 
poorer than optimum in some other respects 
when this is done, since all design represents 
compromises, but the "modern network 
theory" design technique for filters permits 
the designer to choose the performance he 
wants where the "image parameter" 
approach permitted only one or two para- 
meters to be designed for. 

We won't go any deeper than this into 
modern network theory, since it is a 
mathematical technique and one of our 
guiding principles in this course is to stay 
away from all mathematics which we can 
avoid. If you're interested, the fourth 
edition of "Reference Data for Radio 
Engineers" (and presumably the just- 
published fifth edition as well) contains 47 
pages (pages 189 through 235) describing 
the technique* 

We'll merely note that the modern- 
network-theory design approach permits a 
number of different filter response curves, 
and the resulting different filters are usually 
identified by names associated with the 
shapes of these curves. The two most widely 
known are the Chebishev (also spelled 
Tshebysheff, Chevishef, and Tshebishev) and 
the Butterworth filters. The Chebishev 
design provides the sharpest possible rate of 
cutoff at the cost of permitting ripple in the 
passband, while the Butterworth design 
maintains passband response flat at the cost 
of moderate phase shift and less steep cutoff 
rates. 

It may seem a bit odd for us to declare 
that all filters are based upon reactance 
when crystal lattice filters composed of 
several quartz crystals are so widely used, 
but electrically the crystal is just a very- 
high-Q tuned circuit and contains both Xj 
and X e . When used in a filter, the Xj and X c 



provide the filtering action. We'll look at this 
in more detail in a subsequent section. First, 
let's see how filter performance is rated. 

How Is Filter Performance Rated? Filter 
performance is rated according to several 
factors, and the factors involved vary to 
some degree with the type of filter in 
question. One factor present in the rating 
of every filter is its "attenuation"; this is a 
measure of the signal level at the output side 
of the filter compared to the level at the 
input side. 

Every filter possesses some definite value 
of attenuation at every frequency, A low- 
pass filter has attenuation both below and 
above its cutoff frequency, as do highpass 
filters, bandpass, and bandstop varieties. 
Attenuation is usually expressed in dB. 

If the output level at some specified 
frequency is the same as the input level, the 
attenuation at that frequency is 0dB. If the 
output level is zero for any value of input 
level (a condition theoretically possible but 
not attainable in practice because of stray 
coupling around the filter), the attenuation 
at that frequency is infinite. 

A plot of attenuation versus frequency 
gives the "response curve" of the filter. Fig. 
9 shows typical response curves for the four 
categories of filters. 




LOWPftSS 



t — * 

HlGHRftSS 





BAJtDRASS 



BANDSTOP 



Fig, 9. Typical response curves of the four 
major categories of filters. These response 
curves are idealized; actual response curves 
have more rounded corners and never quite 
reach the zero-output point. 

Another factor in common for all filters 
is "cutoff frequency/' but now that we have 
established the meaning of "attenuation" we 
are in position to define cutoff frequency 



110 



73 MAGAZINE 



more accurately than we did earlier. The 
cutoff frequency for a given attenuation 
may be specified as the frequency at which 
the filter has that value of attenuation. Thus 
the 3 dB cutoff frequency for a lowpass 

filter will be lower than the 6 dB cutoff 
frequency. The definition we developed 
earlier-that frequency at which output level 
is half of input level— actually defines the 6 
dB cutoff frequency of any filter. 

A glance at Fig, 9 will show that both 
bandpass and bandstop filters have not one 
but two cutoff frequencies, since for any 
specified value of attenuation there is a 
frequency below the filter's center fre- 
quency which has that attenuation, and 
another frequency above center frequency. 
Xhe two cutoff frequencies of band filters 
are designated as "upper" and "lower" 
cutoff frequencies. 

Sometimes filters are compared according 
to their "slope" or "cutoff rate." This is a 
relative term referring to the rate at which 
attenuation changes with frequency. 
Engineers speak of slope or cutoff rate in 
units of "dB per octave"; this means the 
number of dB change in attenuation when 
the frequency is doubled- A single reactance 
has a slope of 6 dB per octave; that is, if 
frequency is doubled the reactance is either 
doubled or halved, and the resulting ratio is 
6 dB (2:1 voltage or current, and 4:1 power 
ratio). Filters with two reactances usually 
have slopes of 12 dB per octave, with the 
slope increasing 6 dB per octave for each 
added reactance in the filter. This is not an 
airtight law-, however; many filters have 
slopes which do not follow this rule, and 
almost no filter follows this rule at frequen- 
cies near the cutoff point or within the 
passband. 

All filters have a "bandwidth," but the 
term has different meanings depending on 
whether the filter is (1) lowpass or highpass, 
or (2) bandpass or bandstop. For lowpass or 
highpass filters, the bandwidth for a speci- 
fied attenuation is the actual frequency at 
which the filter has that attenuation. The 
"width" means the number of cycles from 
zero frequency to the frequency in question. 
Thus the bandwidth for 3 dB attenuation of 
a lowpass filter with a 3 dB cutoff frequency 
of 100 Hz is 100 Hz. 



For symmetrical bandpass or bandstop 
filters, the bandwidth is the difference (in 
hertz) between the two cutoff points for the 
specified attenuation. A bandpass filter with 
an upper 3 dB cutoff frequency of 10 kHz 
and a lower 3 dB cutoff frequency of 8 kHz 
would have a 3 dB bandwidth of 10-8 or 2 
kHz. 

Bandwidth is always specified for a 
definite attenuation level, because it is 
defined in terms of cutoff frequencies, 
which are themselves defined only by atten- 
uation level. Unless the attenuation level is 
specified, any use of "bandwidth" as a rating 
factor is meaningless. 

For bandpass filters in particular, the 
bandwidth is one of the primary measure- 
ments-but it is by no means the only one. 
Consider two different bandpass filters, both 
having 6 dB bandwidths of 3000 Hz. The 
first, however, is a very simple filter with 
only a few reactances and consequently has 
a very slow rate of cutoff, while the other is 
a complex Chebishev design with steepest 
possible cutoff rate. The first filter may have 
a 60 dB bandwidth of 30 kHz and the 60 dB 
bandwidth of the second might be as narrow 
as 6 kHz. (Fig. 10). 



-60dB 




Fig. 10. Significance of "shape factor" is 
shown here. Both filters whose response 
curves are illustrated have 6 dB bandwidths 
of 3 kHz. That in solid lines has a 60 dB 
bandwidth of only 6 kHz, while that in 
dotted lines has 60 dB bandwidth of 30 
kHz. Difference in effective passband is 
clearly evident. 

Obviously, the second of these filters will 
do a far better job of trimming applied 
signals down to its passband. 

The term "shape factor" is used to 
describe the property we have just com- 
pared; the "shape" referred to is that of the 



73 MAGAZINE 



111 



filter's response curve, A perfect bandpass 
filter would have absolutely vertical sides to 
its response curve } with zero attenuation 
between the two cutoff frequencies and 
infinite attenuation outside that range. 
Actual bandpass filters have response curves 
which vary from a barely perceptible hump 
up to a steep-sided curve very much like that 
of the perfect filter. 

The "shape factor" of a bandpass filter is 
the ratio between its bandwidths at two 
different attenuation levels. In ham practice, 
the 6 dB and 60 dB bandwidths are the ones 
most often used. The shape factor ratio is 
always obtained by dividing the larger band- 
width by the smaller, so that it is always 
greater than 1. A perfect filter with vertical 
sides to the response curve would have the 
same bandwidth at all attenuation levels, and 
so would have a shape factor of L Practical 
filters always have greater bandwidth at high 
attenuation levels than they do at the 
lower-attenuation points, and so their shape 
factors are always greater than 1. If the 6 dB 
bandwidth of a filter is 1.5 kHz and the 60 
dB bandwidth is 3.0 kHz, the 6-60 dB shape 
factor of that filter is 3.0/1.5 or 2; this 
represents excellent performance. Many 
bandpass filters in use today have shape 
factors as great as 10. The shape factor of a 
single tuned circuit when used as a bandpass 
filter may be as great as 100, 

How Are RF Bandpass Filters Con- 
structed? One of the requirements for any 
receiver intended to operate in today's 
crowded rf spectrum is that it have extreme 
selectivity. Ideally, it should be able to tune 
in either sideband of an AM signal while 
rejecting both the carrier and the other 
sideband. This is known as selectable side- 
band capability, and marks an extremely 
selective receiver. 

Almost universally, such selectivity is 
achieved by use of bandpass filters operating 
in the rf or i-f range. Since normal i-Fs are 
actually radio frequencies, we'll lump these 
filters together for our discussion. 

RF bandpass fillers capable of providing 
shape factors smaller than about 10 are most 
often one of two major types -mechanical 
filters and crystal filters. We won't go into 
details of the mechanical filters here, since 



they have little to do with electrical and 
electronic phenomena. 

Crystal filters themselves divide into two 
major groups. One of them uses only a single 
crystal, to provide a very narrow response 
curve with relatively poor shape factor. This 
type, which was standard equipment on 
older communications receivers, provides 
excellent results on CW but is not so hot for 

reception of voice signals. The second group, 
which used two or more crystals, provides 
greater bandwidth than the first, with 
smaller shape factor. It is widely used in SSB 
operation, since the shape of its response 
curve matches the requirements for voice 
communication. 

The single-crystal type of filter is nor- 
mally known simply as a "crystal filter," 
while those using two or more crystals are 
generally called "crystal lattice fUters." 
Technically, a lattice filter must use four 
crystals t or multiples of four, but an electri- 
cally equivalent circuit called a "half-lattice" 
requires only two crystals, and is possibly 
the most popular type of lattice filter in use 
now. 

Let's examine both groups of filters 
separately, taking the older single-crystal 
filter first. The schematic of a typical single- 
crystal filter circuit appears in Fig. 11, The 
driving transformer splits the signal into a 
pair of signals, equal in strength but opposite 
in phase. One of these two signals is applied 
to the quartz crystal while the other is 
applied to a "phasing condenser" which is 
simply a variable capacitor. The two signals 
are then put back together at the input to an 
amplifier stage. 




Fig, 1 1. Typical single-crystal if filter of 
type used for CW reception. Adjustment of 
capacitor tunes out parallel resonance of 
crystal to give symmetrical passband, or can 
move parallel resonance to either side of 
series resonance to insert a "rejection 
notch" anywhere within passband except at 
series-resonant frequency itself. 



112 



73 MAGA2INE 




The quartz crystal is equivalent to a very 
high Q resonant circuit; it has both series 
and parallel resonances. At the frequency of 
series resonance, it is an extremely low 
resistance, while at the frequency of parallel 
resonance it is an extremely high resistance. 
In the absence of the phasing condenser, this 
circuit would permit signals at series 
resonance to pass through almost un- 
changed, while attenuating signals at other 
frequencies greatly and providing almost 
infinite attenuation at parallel resonance. 

The phasing condenser, however, provides 
an alternate path for the signal around the 
crystal. When the phasing condenser is 
adjusted so that its capacitance exactly 
balances the parallel capacitance of the 
crystal and its holder, the parallel resonance 
of the crystal is eliminated and the filter's 
response curve becomes a single sharp peak. 
The rejection notch at parallel resonance is 
eliminated. 

When the phasing condenser is adjusted 
for either more or less capacitance than that 
required to balance the crystal, the effect is 
to tune the parallel resonance of the crystal 
to some definite frequency. This introduces 
the rejection notch, and makes it possible to 
move the rejection notch relative to the 
passband peak, permitting a single inter- 



> z * * 




Fig, 12. Full-lattice filter arrangement in 
block diagram form. Each block represents 
an impedance having characteristics of the 
circuit shown ?n Fig, 13, When intercon- 
nected as shown here, passbands of "A" and 
'B" sections interact to provide a flat- 
topped passband with excellent shape fac- 
tor. 




TERMINALS 



Fig. 13. Equivalent circuit of each impe- 
dance in full lattice filter. ParaffeJ-resonant 
circuit at left represents parallel resonance 
composed of crystal and stray circuit capaci- 
tance, together with loading resistances, 
Series-resonant circuit at right (which may 
be extended indefinitely as indicated by 
dotted lines) represents series resonances of 
each crystal in each leg. Impedances "A" 
and "B" are parallel resonant at lower 
cutoff frequency. Series resonances intro- 
duce ''infinite rejection" notches just out- 
side passband to sharpen skirts of filter. 



fering frequency to be "notched out" of the 
signal. 

Adjustment of resistance Rl modifies the 
loading imposed on the filter, and varies the 
effective bandwidth. The 6 dB bandwidth of 
such a filter circuit can be varied from about 
50 Hz when Rl is extremely large, out to 
greater than 6 kHz when Rl is very small 

The multiple-crystal filter designs are 
based on the lattice structure shown in Fig. 
12. Each section of this lattice structure 
consists of one or more crystals, and pro- 
vides the equivalent of the circuit shown in 
Fig, 13. Much of this circuitry can be 
eliminated by replacing the lattice with its 
equivalent shown in Fig. 14; the lattice arms 
themselves now require only single quartz 
crystals using their series resonances. 

Characteristics of such a filter are deter- 
mined primarily by the number of crystals 
used, and the degree to which they are 
matched* Those crystals marked A and those 
marked B must not tune to the same 
frequency. In fact, the spacing between the 
series resonant frequency of crystals A and 
that of crystals B is the major factor 
determining the filter's bandwidth. 

Design of such a filter is done by modern 
network theory, usually using the Chebishev 
techniques, and is too complex for us to 
explore here. In general, the bandwidth 
determines the spacing between resonant 



FEBRUARY 1970 



113 




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Fig. 14. Load resistances and stray circuit 
capacitance of full lattice filter can be 
moved to input and output terminals as 
indicated here, This circuit is electrically the 
same as that of Fig. 12. Each "A" and "B" 
block is still the circuit of Fig. 13, which 
may in practice consist of a single crystal for 
each block. 



frequencies of the two groups of crystals. 
Within each group, characteristics of each 
crystal must match as closely as possible 
(many commercial crystal filters use a single 
crystal with multiple electrodes on it, each 
pair of such electrodes serving as a "dif- 
ferent" crystal in the lattice, to assure 
identical characteristics). So long as the 
filter's center frequency is not greater than 
about 250 times its desired bandwidth, ^ood 
shape factor can be attained easily. That is, 
for a "phone" bandwidth of 3 kHz, any 
center frequency up to 750 kHz could be 
employed. In fact, successful lattice filters 
with center frequencies as high as 10 MHz 
and bandwidths as small as 2 kHz have been 
built, but design is more critical, 

. . . j lai i 



YOUR CALL 

Please check your address label and make sure 
that it is correct* In cases where no call letters 
have been furnished we have had to make one up* 
If you find that your label has an EE3*4* on it 
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114 



73 MAGAZINE 




Paul Franson WA4KRE 
7430 E. Mmnezona Ave. 
Scousdale AZ 85251 



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■ 



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• * - * 



THEY'RE NEW, HOT, AND CHEAP ! 



Hams have been using integrated circuits 
almost since they were first introduced 
commercially at reasonable prices. The ear- 
liest ham uses were keyers and frequency 
standards using digital ICs. ICs are so useful 
in these applications that it is difficult to 
imagine anyone building a keyer out of 
discrete semiconductors, or (perish the 
thought) vacuum tubes, anymore, ICs with 
their low- voltage operation and great circuit 
simplification make even complex projects 
relatively easy and inexpensive to build. 

The resistor-transistor logic (RTL) family 
(the Motorola MC700P series and the Fair- 
child /iL900 series) has been the most popular 
type of integrated circuits for experimenters. 
Both are packaged in inexpensive plastic 
cases, and though the Motorola devices have 
won out in most uses because they are lower 
in cost and furnish more functions per 
package, many of the Fairchild parts have 
also been used. 

There has been relatively little 
use by hams of linear integrated 
circuits up to now, though a few 
of the audio power amplifiers that 
have been introduced by RCA, 
Motorola, and GE in the past 
few years have seen some use. 
This would be surprising at first 




glance because most ham applications are 
linear or analog ones, rather than digital. 
However, the digital circuits were much 
cheaper and more widely available, hence 
attracted more attention in the past. 
Recently, however, many different types of 
linear integrated circuits have become very 
attractive for ham use. They are now avail- 
able at reasonable prices for many applica- 
tions. 

Many of the new linear integrated circuits 
that are of particular interest to hams have 
been designed for consumer use. This assures 
that they will have reasonable prices; expen- 
sive ICs can find little use in consumer 
equipment. Table I lists many of the linear 
integrated circuits that are now available. 
They include voltage regulators, audio ampli- 
fiers of various types, i-f amplifiers, a unique 
new circuit called the balanced modulator, 
and operational amplifiers. Any one of these 
ICs can replace many discrete devices, and in 

many cases can provide much 
higher performance than any 
practical combination of discrete 
devices could. They also are rela- 
tively inexpensive, ranging in 
price from $1.50 for an i-f ampli- 
fier to $7 J 5 for the balanced 
modulator/demodulator, a recently 



605 



FEBRUARY 1970 



115 



Fig. J. High-performance 1C regulator 
using the MCI 460. The input voltage, 
Vjn must he at least 3V greater than the 
output. Maximum input for the MCI 460 
is 20V. The MCI 460 is good for 35V 
input. An etched circuit board is recom- 
mended for construction. Use VHP tech- 
niques. 



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2 7 



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.ft 



Rl ^_ 



MCI 460 



o2 



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introduced part, AH of the parts described 
are manufactured by Motorola y and are 
readily available from the many Motorola 
distributors, including Allied Radio and 

Newark. 

Voltage Regulators 

One of the most dramatic examples of 
the simplification that a linear integrated 
circuit can provide in a circuit is the voltage 
regulator. 

The MCI 460 series of voltage regula- 
tors can provide up to 600 mA of out- 
put current at over 30V with no external 

transistors or other semiconductors. Only a 
few small resistors and capacitors are 
required to produce a complete regulator 
with excellent characteristics. 

Four members of the MCI 460 family are 
of particular interest to hams. The MCI 460 
has a maximum input of 20V and the 
MCI 461, a maximum input of 35V. The 
"G" versions (in a package very much like 
the TO-66 case used for silicon power 
transistors except that it has 9 pins instead 
of 2) can handle 600 mA when it's mounted 
on an adequate heatsink. Four similar regula- 
tors are available in the MCI 560 series with 
a full temperature range which makes them 
more suitable for military use. They cost 
significantly more. 

The MCI 460 series has a typical low 
output impedance of only 0.025-0.03 5fl at 
frequencies up to 100 kHz, Regulation for 
changes in input voltage is typically only 
0.003% per volt, a remarkably low figure. 
The MCI 460 can put out voltages as low as 
2.5V and as high as 17V. The output voltage 
must always be at least 3V less than the 
input voltage for the regulator to work 
properly- Another interesting feature of the 
MCI 460 series is its short-circuit protection. 



The regulator will not be damaged by a 
continuous short circuit. 

A basic MCI 460 circuit is shown in Fig. 
1. It can put out a maximum of 250 mA* It 
uses only a few small 0.25W resistors and 
capacitors. In the circuit, resistor Rl is 
selected to give the desired output voltage. A 
potentiometer can be used for a variable 
output, but this circuit is really more suit* 
able for a fixed rather than a variable 
voltage, 

The regulator as shown will limit output 
current to 250 mA. If you try to draw more 
current than this, the regulator will auto- 
matically reduce the output voltage. This 
short-circuit current is determined by the 
2,5fi resistor connected to pin 1. This 
resistor can be changed to get other max- 
imum output currents. 

The MC1460G, which is in the TO-5 
package, will require a heatsink for currents 
near its maximum, and the MCI 460 will 
likewise require a heatsink for high current 
values. Probably the most practical type of 
heatsink for the R package is one with a hole 
large enough for all 9 pins to pass through 
without shorting. This is much more prac- 
tical than trying to drill holes for each one 
of the nine pins. A socket is available for the 
MC1460R, but it is hard to find and 
relatively expensive. 

One word of caution if you are used to 
building dc power supplies: The transistors 
used in the MCI 460 are very high-quality 
VHF devices; hence, the circuit must be 
treated properly or it's likely to oscillate at 
very high frequencies. You'll notice in Fig, 1 
that a number of capacitors and resistors are 
included for high-frequency suppression to 
prevent the circuit from oscillating. You 
should use an etched circuit board for 



116 



73 MAGAZINE 



+v 




2N49Q4 



MCI460R 



6B* 



2 0* 



» SiSiV — ^ f 

£ A 




i uf 



t2.7A 



50Ou c 



— —a 

Fig. 2, IC vo/tage regulator with 2A capability 

using external series-pass power transistor. 



constructing this regulator so that you can 
get very short leads and a good ground.* It is 
not practical to go into all the fine points of 
the circuit; however, the data sheet for the 
MCI 460 series is comprehensive and pro- 
vides complete information on using the 
device. 

Two other circuits using members of the 
regulator family are shown in Figs. 2 and 3. 
Figure 2 is a 2 A voltage regulator using an 
external PNP series-pass power transistor. A 
similar technique can be used to provide up 
to 10A for applications requiring this 
amount of current. More information is 
given in the data sheet. 

Figure 3 is a laboratory power supply 
with an output adjustable from to 25V. It 



will provide up to 400 mA* This circuit, 
unlike many power supplies, can go all the 
way down to zero volts. It is also interesting 
because of the extreme simplicity of the 
circuit- It would be interesting to compare 
Fig. 3 with a typical regulated power supply 
using discrete devices. The discrete version 
would be far more complex and expensive, 
and yet would not provide the same perfor- 
mance. 

The Motorola MCI 469 is a regulator 
similar to the 1460, but even less expensive, 
and designed for less exacting uses. No 
circuits are included for this device because 
they were not available at the time this 
article was prepared. However, the data 
sheet on the devices will give considerable 
information, 

Another voltage regulator of particular 
interest is the MCI 466, which is designed for 
use with external transistors. It can be used 
to regulate voltages as high as I000V or even 
higher. In this application, the regulator is 
floating, but it can be protected against 
shorts even though the external pass transis- 
tor used with it may not be able to stand 
this high voltage if the output is shorted. 
More practically, or perhaps of more inter- 
est, the 1466 can be used to provide very 
high current at lower voltages, or provide 
medium current with voltages in the 100 to 



*A board is available for $1.50 from Project 
Supply Company, PO Box 555, Tempe AZ 8528 L 



II0V;45VCT 



MDA920-3 




rr250pF 



fOOp F 



Fig. 3. 0-25 V f 400 mA laboratory power supply. 



FEBRUARY 1970 



117 



AG 1W AU 50 ohm t if ton com ill cable. Ouifidt d>*m*ter 060 J RF 
Ion 29 db p«r foot it 400 Mhr, Siiv«f piittd ihi tiding md conductor 
Ui»d for int*rn«4 chrait wiring, tnl*nn« ooupliog, RF coupling bftfwMn 
itign. etc Random langthi from 35 foot to 150 foot. Colon: black r rad, 
brawn, blu#. gray, oranga Rtgultr prict- 23d par fool Our pric* S* per 
fool S3.00p*r 100 U. 

466 Khi carorruc Mttn tvp* BF-455-A Thaaa filtari will halp to tharpan 
tha adacliviiy of moit iett using 455 Khz I Ft. U« ecroit cathoda bias 
ratiftor in place of a capacitor, or in frentistor i?ed eats, acroai the emitter 
bi« raeirtor Impedance it 20 oh mi at 455Kh*.. DC fetittance it infinite. 
Impedance increeeei rapidly at you laava 455 K hi Plin your own LC 
fiUar circuit* at vary tow coat. * 

10 for $1 00 25 for £2.00 

TOROID POWER TRANSFORMERS 

t 1-2 Thit toroid was das+gned for use in a hybrid F.M, mobile unit, uling 
e tingle B647 tube in the RF amp. for 30 watti output. Schematic in- 
cluded 12 VDC pri using 2N1554i or equivalent, Sec #1 500 volts DC 
out ai 70 warn. Sec. 02 -65 volts DC bias. Sec. *3 1.2 volt* AC for 
filament of 8647 lube Sec 04 CfT feedback winding for 2N 1554 i 1'/." 
thick. 2« ,r d;e $2 99 ee 2 for S5.0O 

# T-3 H« a powdered iron core and is built like e TV fly beck trinsf ormer 
Operates at about BOO CPS. 12V DC Pri. using 2N442 r lor equivalent. DC 
output of V/DBL R 475 volts 90 watts. C/T feed back winding for 2N442't 

$2 95 aa 2 for $5.00 
TRANSFORMERS 

P-7 117 VAC Pri Sec. #1 185 CAV @ 120 ma. Sac. #2 6-3 VAC <P 4 A, 
Double Half Shell Mail Bo* Type SX 146 type $2 75 ee -2 for S5.00 

P-fli 117 VAC Prj Sec. I 90O VAC @ 300 ma. Sec # 2 100 VAC © 10 ma. 
Bias. Sec 03 126 VAC @ AMP. Wt 16V4 lbs. Double Haff Shell $4 50 

P 10 117 VAC Pri. Sec #! 960 VAC C T @ 160 me, Sec. 02 425 VAC 
CT end tap at TOO VAC 10 me Bias. Sec 03 126 VAC © 4.5A Double 
Shell Mail Bo* type. Wt 8% lbs $3.75 

Output transformers, all types 59 cents or 3 tor $1 50. 

OT-1 Transtiior TO-3 Power Ditmond- Imp. 15 ohms to 3-2 ohms DC 
Res. Pri. Sohm Sec .3 ohm. 

OT 2 Pri imp. 7000 ohm Sec. 3-2 and 500 ohm for Phones or 70 volt 
hne 3 wetts Full shielded Double Halt Shell. 
OT3 Pri. imp S500 ohms Sec, 3,2 ohms. SC122type 

All prices FOB All weights listed are net Please allow for packaging. 
Please a flow enoucjh for postage We will return any extra. 

TOWER 

COMMUNICATIONS 

122C22 Villa St., Racine, Wl 53403 



BACK ISSUE GUNSMOKE ! 

30, count *em 30, stupendous tremendous 
(more handbooks than magazines) fascinat- 
ing enormous devastating incredibly ener- 
vating back issues of 73.... ... 

ONLY $5,00 

postpaid worldwide 




Yes.. .yes.. .yes.. .here is a 

golden opportunity to 
low your mind on 30 
back issues of 73. You 
send us $5 in negotiable 
securities, cash or check 
and w© will send you an 
unbelievable miscellany 
of thirty different (all 
different) back issues, 
all from the 1960-1966 
era. These are all rare 
collectors items* Every 
one could likely be wo- 
rth a fortune to you. Who knows, yog might 
even find a rare January 1961 in this pile! We 
don't even know what is in these packages. To 
keep costs down we have had these magazines 
packed into sloppy bundles by the Chimps 
from Benson's Wild Animal Farm (nearby). 
Watch out for banana skins. —If you want 
specific issues of 73 they are available at the 
low low (high) price of $1 each. Unless we 
don't have them, in which case the price is 
higher. —How about sending a bundle to a DX 
friend? Back issues of 73 are worth their weight 
in unicorn dung in most countries, —Money 
received without a shipping address will be used 
for beer. 

73 Magazine Peterborough NH 03458 



200V range. This would be useful, for 
example, as a screen supply for a trans- 
mitting tube. Other voltage regulator ICs are 
available; most are made for use with exter- 
nal transistors for currents of more than 
about 10 mA. 

All in all, the new IC voltage regulators 
make it very easy to design and build a 
power supply to provide almost any current 
or voltage with very little work, and assur- 
ance that the circuit will work properly 
without needing any adjustments. The day 
of the discrete semiconductor regulator 
seems to be rapidly approaching its end. 

Audio Amplifiers 

Many of the new inexpensive linear ICs 
are audio amplifiers. Some are designed for 
low-level use, others for moderately high 
power; that is, a watt or more. Starting at 
the low end of the price and complexity 
scale is the MFC4010, a wideband amplifier 
that can provide up to 60 dB of gain at 1 

MHz, so it's suitable not only for audio, but 
also i-f applications. 

The MFC4010 is one of the first of a new 
breed of consumer ICs. It has only four pins; 
the package is a small version of the dual 
in-line package that has become so popular. 
The four pins are positive voltage, ground, and 
the input and the output. That's all; no 
complex compensation is needed as has been 
required in the past for most ICs. 



+ 6V 



IK 



IWKE O vv^ *- 




3 9k 30 k 



560*t 
-mw — 



3>3T 



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Fig. 4. High-gain audio amplifier using MFC4010 
wideband amplifier* 

The MFC4010 is especially useful as a 
microphone amplifier or as a general-purpose 
455 kHz i-f amplifier. A typical circuit using 
this device is shown in Fig, 4. It operates 
from 6V; it's an audio amplifier for a 
microphone, and as you can see, very few 
external components are required to provide 
high gain. The MFC4010 itself contains 
three transistors and five resistors. 



118 



73 MAGAZINE 







Another low-level audio amplifier is the 
MC1303P in the popular dual in-line 14-pin 
package. This dual audio amplifier was 
designed to be used as a preamplifier in 
stereo phonographs and similar equipment. 
It provides 60 dB of gain and is useful where 
high gain and two separate amplifiers are 
needed . 

The MFC4000 is a 0.25 W audio power 
amplifier with 15 mV sensitivity. It contains 

six transistors, three diodes, and five resis- 
tors. The MFC4G00 uses the same small 
package as the MFC4010 and also has only 
four terminals: inputs output, supply volt- 
age, and ground. Its 250 mW of audio output 
may not seem like much, but it is quite 
satisfactory for many applications, such as 
pocket radios, and home equipment, where 
the noise level is not very high. When used 
with an efficient speaker, that quarter watt 
will drive you out of the room. 

The MFC4000 draws very low standby 
current, typically only 3.5 mA at 9V. 
Perhaps the best feature of the MFC4000 is 
compactness. A whole audio output stage 
takes up very little space. 

The MC1306P is also a 250 mW audio 
amplifier, but it includes a preamplifier* 
giving it a sensitivity of 3 mV for full 
output— considerably higher gain than the 
MC4000, It's packaged in a new eight-pin 
plastic package that looks like a shortened 
dual in-line package. Four transistors in the 
preamplifier section and ten transistors in 
the output section are contained in the small 
package. The two parts are independent and 
can be used in cascade with other circuitry, 
such as a volume control or filter between 
them. Like the MFC4000, the MC1306P is 
designed for 9V operation and has a similar 
low zero-signal current drain (4 mA). Typi- 
cal harmonic distortion is only 1%, 

A typical application of the MCI306P is 
shown in Fig. 5. This is a high -gain 250 mW 



audio amplifier for use in a portable receiver. 
Its total gain is 1000, or 30 dB. Only a few 
external components are required, but as 
with all these ICs, the component leads 
should be short to prevent high-frequency 
oscillation. 

The next IC has been available for some 
time in an expensive hi-rel (military term for 
"high reliability") version. The recent intro- 
duction of a low-cost, relaxed-spec version 
makes it much more interesting. This device 
is the MC1454G. It is similar to the older 
MC1554G, but as mentioned, has relaxed 
specifications and a much lower price, $3,30 
instead of $14.25. 



V* - I4V 



V IN * 




8n 



Fig. 6, Audio power amplifier has 1 W gain of 1 0; 
input impedance of 10 k£l An external heatsink 
is required. The HEP593 can also be used in this 
circuit with similar results. 



Figure 6 shows a 1W audio power ampli- 
fier. You'll notice that it uses no trans- 
formers, and operates directly from 12.5 to 
14V. The gain of this circuit is 10, and the 
input impedance is 10 k£2. An external 
heatsink must be used with this device for 
maximum power output. 

The HEP 593, readily available at almost 
all electronic stores in the country, is similar 
to the MC1454G. Either of these devices 
makes an excellent output amplifier for use 
in mobile or home equipment. Its IW of 
audio power is adequate for most ham uses, 



5* 






m 




16 a 



Fig, 5. High -gain (30 dB) 2S0 mW audio amplifier 
for use in portable receiver. 



FEBRUARY 1970 



119 



50a 




4 3 2 

MCI350P 
(Top View) 

5 6 7 



AGC 

(50V) 




Hi«r?°- 



OUTPUT 



% 



Component 




Frequency 




455 kHz 


10.7 MHi 


45 MHz 


CI 


— 


SO 450 pF 


9.0-35 pF 


G2 


— 


5 80* pF 


2.0-8.0 pF 


C3 


05 jjF 


001 ,iF 


0001 jjF 


C4 


05 nf 


0.05 jiF 


0.001 uF 


CS 


0,001 uF 


36 pF 


1.0 5.0 pF 


Co 


G\05jjF 


05 mF 


001 pF 


C7 


0,05 mF 


0.05 mF 


0.001 uF 


LI 




4.6 ,u.H* 


8/iH 


T1 


Note 1 


Note 2 


Note 3 



'Circuit positions of LI arid C2 are interchanged 

Fig. 7. High-gain i-f amplifier with wide-range age 
10.7 MHz, and 45 MHz. 



Note V Primary 120 m h teenier tapped) 
U u " 140 31 455 kHz 
Primary Secondary turns ratio ^ 1 3 

Note 2 Primary 6.0 pH 

Primary wmdmg = 24 turns 036 AWG (close wound on 

1/4" dia- form* 
Core ■ Arnold Type TH or equiv 

Secondary winding - 1-1/2 turns #36 AWG, 1/4" dia. 

(wound over center tap) 

Note 3 Primary winding = 18 turns ^22 AWG (center tapped) 

Secondary winding = 1 turn #22 AWG I over- wound at 

cantor of primary) 



act/on. Circuit values are shown for 455 kHz, 



except modulating large AM transmitters, 
which hardly anyone does any more. Motor- 
ola Application Note AN-401, 'The 
MCI 554: A One-Watt Monolithic Integrated- 
Circuit Power Amplifier/ 1 gives more infor- 
mation on applications of this useful circuit. 
As mentioned, the MCI 454 is a relaxed 
version of the MCI 554, and the circuits 
described apply in almost cases. 

1-F Amplifiers 

A number of new i-f amplifiers have been 
introduced recently; many are of great 
interest to the ham. In addition, one that's 
been around for a few years takes on a new 
interest in view of its recent reduction in 
price from $4.25 to $1.50. 

The MCI 35 OP is perhaps of greatest 
interest. It features very high gain at fre- 
quencies up to 60 MHz and also includes 
provision for very wide-range age. Power 
gain is typically 50 dB at 45 MHz, and age 
range is 60 dB minimum. It has very low 
feedback capacitance, thus does not need 
neutralization in spite of its very high gain. 
The device is designed for operation on I 2 V 
from a single power supply, unlike many of 



the earlier ICs. The MC1350P was designed 

for use in television receivers; however, it*s 
equally valuable for many other uses, such as 
i-f amplifiers at any frequency up to 60 
MHz. Typical gain at 45 MHz is 50 dB; at 
10.7 MHz, it's 58 dB, and at 455 kHz, 62 
dB. Noise figure at 60 MHz is a respectable 9 
dB, but you probably would want to use a 
low-noise preamp if you were using this i-f 
amplifier in a microwave receiver. For other 
applications, this noise figure is more than 
adequate. Typical circuits for the MC1350P 
are shown in Fig, 7. Component values are 
given for frequencies of 455 kHz, 10,7 MHz, 
and 45 MHz. 

Very similar to the MC1350P is the 
MC159GG, a higher-performance version 
sealed in a metal can for use in military 
equipment. The MC1590G costs S5.60 in 
single quantity, so you can see that the 
MC1350P at $3,75 would be of much more 
interest in most ham applications. 

Either the MC1350P or the MC1590G 
also makes an excellent video or audio 
amplifier for any application requiring very 
wide range age, such as speech compression 
circuits. 



120 



73 MAGAZINE 



'399 1 



' '.A 



m 

or 16mm 

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. S245.00 



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An exceptional buy in a first quality new Cannon Zoom lens for your TV 

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PO Box 85, Longview St. 






A very simple receiver providing quite 
good performance could be made using a 
few of these integrated circuits. Discrete 
dual-gate MOSFETs are better in the front 
end: an MFE3007 is an excellent rf ampli- 
fier, An MFE3008 mixer with a separate 
oscillator could feed an MCI 3 SOP i-f ampli- 
fier, then a detector and MC1306P audio 
output amplifier. 

An older, but very good, linear IC is the 
MC1550G rf/i-f amplifier. This is a much 
simpler circuit than the MC1350P, but it 
also offers very wide age range, high power 
gain (typically 30 dB at 60 MHz), good noise 
figure, and extremely low feedback capaci- 
tance. The MC1550G used to cost $4.25; 
now it's down to only $1.50, which makes it 
very attractive for many applications. 




50* 

LOAD 



Fig, fi. MHz amplifier with 25 dB gain and good 
age characteristics. The HEP 590 can also be used 
in this circuit with similar results. 

Many circuits have been described using 
the MC1550G, increasing its appeal to the 
ham builder. A typical example is shown in 
Fig. 8. This is a 60 MHz amplifier with 25 
dB gain; it can furnish excellent age. Motor- 
ola Application Note AN-247 "An Inte- 



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FEBRUARY 1970 



121 



grated Circuit RF/IF Amplifier," provides 
more information on using the MC1550G. 

The HEP590 is similar to the MC155QG. 
Both are packaged in the TO-5 metal can. 

One of the most interesting of new linear 
integrated circuits is the MCI 35 IP* This 
wideband FM amplifier provides i-f amplifi- 
cation, limiting, detection, and audio ampli- 
fication. This circuit is almost a complete 
FM receiver, fitting in well with the recent 
amateur repeater trend. The MCI 35 IP typ- 
ically has 65 dB gain. It uses an inter- 
esting FM detector that requires only one 
external coil and capacitor in its reso- 
nant circuit. 

The MCI 35 I P was designed for use in the 
4.5 MHz sound channel of television receiv- 
ers (5.5 MHz for Europeans); however, it's 
very adaptable for use in FM receivers, either 
commercial FM broadcast receivers at 10.7 
MHz, or in mobile communications receiv- 



ers, A typical circuit using the MC1350P is 
shown in Fig. 9, This is a complete FM i-f 
system. It is most adaptable for use in the 
home, since it requires MOV dc for the 
audio power amplifier. However; a similar 
type of circuit can be used at 1 2V with a 
different audio amplifier. Motorola Applica- 
tion Note AN-468, t4 A Monolithic Circuit 
for Television Sound Systems/" describes the 
use of the MCI 35 IP in TV reception. The 
ham can easily convert this for FM reception 
in communications work. 



Balanced Modulator 

An interesting new linear IC is the 
MC1596G balanced modulator/demodula- 
tor. This circuit is a complete SSB product 
detector or a balanced modulator for genera- 
ting DSB with no coils or external tuned 
circuits. It requires only a few resistors and 



0.01 ^F 
INPUT O 1£ 



50 pF 




0.1 jiF 



25 k 

VOLUME 
CONTROL 



0.5 W at 7.5 kHz Deviation 

3.5 W at 25 kHz Deviation 



O *240 V 



MJE340 OR EQUIV 



vec - "- s 

0.031 



Fig, 9. Complete FM i-f system* Though this circuit was designed for use in TV receivers, it is also 

excellent for ham FM reception. For portable use, another type of output stage would be preferable. 



122 



73 MAGAZINE 



capacitors. Figure 10A is a typical balanced 
modulator circuit using the MC1596G, 
Figure 10B also shows the typical double- 
sidebandoutput spectrum that it produces. 
The 500 kHz carrier is completely elimi- 
nated, at least to the definition of the 
spectrum analyzer used, about 60 dB down. 
The MCI596G can easily provide 40 dB of 
carrier suppression at 9 MHz, perhaps the 
most popular frequency for generating SSB 
signals these days. 



?r S^fl 



/T7 rh 



agc 

(SOV) 



3.1k 



03 



B 



4 J 2 

MD35GP 
( Top Vtew *t 

5 6 7 



C7 



r 




5oa 

OUTPUT 



rn 



Fig, JO (A). Balanced modulator using MC1596G 
and (B) double-sideband output spectrum. Carrier 
rejection is greater than 60 dB without using any 
coils. 



B 




At $1.75, the MC1596G is not inexpen- 
sive; however, its versatility and the simplifi- 
cation and high performance it brings to a 
circuit should make it very popular and we 
will likely see many applications of this type 
of device in the future. 

Incidentally, to those of you who follow 
the engineering magazines, the MC1596G is 
a simplified cousin of the MCI 595 multiplier 
that has been attracting a great deal of 
attention. The monolithic multiplier seems 
to be the new analog building block, similar 
to the op amp in its versatility, and can be 



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USED TEST EQUIPMENT 

All in Good Working Condition 

H-P 200AB audio oscillator, rack 

mount , $ 60,00 

Ballantine 300 AC vtvm 3 25.00 

Measurements 111 crystal calibrator , , S 60.00 
Measurements 71 sq. wave generator . . $ 60.00 
Tektronix 1S0A time-mark generator . 3150*00 
Fluke 101 VAW meter w/3 shunts . , . 3150.00 
Triolab 131-1 phase-sensitive ac vtvm r 

full scale, 1 mV to 300V near new . . ,$150.00 
Precision E-200 C sig, gen. 90 kc-30 mc$ 35,00 
Dumont 294-A 5" scope. Response to 

12 mc, high voltage acceleration for 

photography of transients, scope & 

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Hickok 610 TV sweep generator, less 

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Distributors for 
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You can also trade your excess test equipment 
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Send 104 for flyer listing surplus elec- 
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Please include sufficient shipping charges with 
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4252 Pearl Rd. Cleveland. Ohio 44109 



FEBRUARY 1970 



123 




+ Bv 




Carntr >npur 

O 

300m v cm* 



SSB ,V 
Signal 
input 
5-5Q0mv 




3 9 I 



0,005^ 



Unmodulated 
AF 
Output 



■ ,; - I Ifr- 

—1— — I— lyr 

coos T* 'Tq.OQSi* 
wf ft? ft? 



&QP 



Fig. 1 1, Product detector using MC1S96G balanced 
modulator/demodulator. 



used in many different applications. The 
MC1596G is considerably simpler and less 
expensive; however, it still provides excellent 
performance in many applications. 

Operational Amplifiers 

Many circuits have been described using 
operational amplifiers, or op amps, Op amps 
have been around for many years, and cost 
as much as $200 at one time. Now you can 
buy a very high-quality, high-gain opera- 
tional amplifier, the MC1439L, for only 



$2.70 in single quantities, This op amp is a 
relaxed version of the MCI 539, which is 
widely used in military and commercial 
equipment. This circuit, though inexpensive, 
is extremely versatile, and can be used in 
almost any circuit requiring an op amp. 

Conclusion 

This article has provided a quick look at 
some of the new linear ICs of particular 
interest to hams. It has provided only very 
sketchy information, however. For more 
information on any device in which you are 
interested > you can write to the Technical 
Information Center, Motorola Semicon- 
ductor Produrt^ Inc., PO Box 20924, 
Phoenix ,AZ 85036, The data sheets on the 
devices provide a great deal of information ? 
and where mentioned, application notes are 
also available. 

I hope this description of these circuits 
helps to convince you that linear ICs are 
now at the stage where hams can use them in 
their equipment. They are more economical 
circuits using discrete devices in many cases, 
and are much easier to work with. 

... WA4KRE" 



Table I. Linear ICs of Particular Interest to Hams 



TYPE 




i 

PRICE 


NUMBER DESCRIPTION 


CASE 


( 1 -99) 


Voltage Regulators 






MC1460G 20V, 250 mA 


602A 


$5.25 


MC1460R 20V, 600 mA 


614 


6.75 


MC1461G Voltage Regulators 35V, 250 mA 


602A 


6.79 


MC1461R 35V, 600 mA 


614 


8.25 


MCI 469 R 35V, 600 mA 


614 


6.75 


Audio Amplifiers 






MFC4010 Wideband amplifier, 60 dB gain, to 1 MHz 


629 


1.85 


MC1 303P Dual audio preamplifier, 40 dB gain 


605 


5.25 


MFC4000 250 mW audio power amplifier, 15 mV sensitivity 


629 


2.10 


MC1306P 250 rnW audio power amplifier, 3 mV sensitivity 


626 


2.90 


MCT454G* 1W audio power amplifier 


602 B 


3.30 


IF Amplifiers 






MC1350P Age rf amplifier (to 60 MHr) # 58 dB gain at 10.7 Mhh 


:626 


3.75 


MC1550G** Age if amplifier (to 100 MHz), 25 dB gain at 60 MHz 


602 B 


1.50 


MCI 35 IP |-f amplifier, FM detector, audio preamplifier 






65 dB gain at 4,5 MHz 


605 


4.10 


Balanced Modulator 






MC1596G Balanced modulator/demodulator, 40 dB carrier 






suppression at 10 MHz 


602A 


7.15 


Operational Amplifier 






MC1439L High-gain, high-performance op amp 


605 C 


2.70 



•The HEP593 is simitar 
**The HEP590 is similar 



629 





632 




602 




614 




124 



73 MAGAZINE 



The editors and Engineers Radio Handbook is by far the biggest and the 
best handbook in print. Here is your chance to get this great book at a 
substantial discount, if you act fast. We have just 500 copies on hand and 
when they are sold that will be the end of the bargain. You either will get 
one of these 500 or else have to pay the full price to buy this fabulous 
handbook. 



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data covering every aspect of 
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Ten dollars doesn't stay 
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but this book will be fun to 
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74 Pine Tree Lane 
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THE GLOP WILL GET YOU- 
YOU DON'T WATCH OUT 






This is an old story but it's worth 
telling again. Twinlead can deteriorate in its 
performance at radio frequencies, especially 
when it's wet. This is old hat to most hams 
that have been around a while, but we tend 
to forget. This forgotten point was re- 
emphasized to me a few nights ago. I tried to 
fire up the rig on my favorite band, but the 
antenna just wouldn't take any power. All 
received signals sounded normal, so my 
suspicion was directed to the twinlead; 
about 75 feet of it feeds the antenna. 

There had been a small rain shower, and 
the twinlead was covered with a thin layer 
of moisture, something resembling dew, 
Since it was late, I resolved to do something 
about it the first thing in the morning. Next 
day, the flat-top was lowered and the twin- 
lead was scanned. Sure enough, there was a 
thin coating of dirt, dust and a dark sooty- 
looking compound. This was carefully re- 
moved with a soft piece of paper towel, 

which had been dampened with water. It is 
surprising how this stuff will pile up on your 
antenna insulators and transmission line* 
This is the same stuff that attaches itself to 
your car, only you are more aware of it since 
you must see through the windshield in 
order to drive. It's also piling up on your 
antenna system at the same time, the big 
difference being that you can't drive your 
antenna to the carwash every time it ac- 
cumulates a fresh layer of dirt. But it's piling 
up nevertheless. 

This is not something peculiar to the 
amateur fraternity. Couple of years ago, 



there was a big blackout in a Canadian 
province. It turned out that carbonaceous 
compounds had attached themselves to the 
high tension insulators— those big six foot 
insulators— and the next time it got damp, 
the circuits arced over. Everyone gave up 
on TV for that night, and went back to 
candles for light! 

Once the black glop is wiped clear of 
your twinlead, it is fairly simple to wipe a 
little "magic compound" over the twinlead 
and your troubles will be gone for guite a 
while. The magic stuff in this case is the 
Dow Corning type 4 compound, a silicone 
base surface-coating compound, sometimes 
called "DC-4.** This stuff will make your 
twinlead shrug off water like a duck's back* 
It is available at Allied Radio and at other 
well-stocked suppliers. The cost is $2,00 for 
a two ounce tube. At first blush, this may 
seem rather high. But you don't smear it on, 
you wipe it on with your fingers. And 
remember only a thin, thin layer is needed. 
Anything thicker than one molecule deep is 
unnecessary. I have a tube on hand that's 
been around for years. Sure it*s an old story, 
but worth telling once more. 

By the way, you can use the same 
compound for waterproofing the ignition 
wires and other components in your car 
which handle high voltage. The family car 
will be less prone to fail when you drive 
through a deep puddle, and the XYL will 
think you're an electronic genius. 

...W20LU" 



126 



73 MAGAZINE 



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— 



(continued from page 12) 

Mismanagement, Incompetence, or Both? 

Dear Mr, Green: 

Your November editorial and Dave Mann's 
article regarding the ARRL were a pleasure to read. 
My experience as a ham has been limited as I have 
held a General license for less than six months. I 
have no basis to judge your statements regarding 
ARRL's Kick of leadership and initiative In the 
technical areas surrounding amateur radio, How- 
ever, as an attorney, I feel competent to comment 
on the other matters raised. 

If what you have reported is true. I must 
conclude that the leadership of ARRL is grossly 
incompetent* dedicated to the demise of amateur 
radio, or mismanaged in order to suit the self- 
interest of a select few, A viable, dynamic com- 
pany or organization, if it is seeking its greatest 
productive effort, cannot afford to hold 
$tf 18,000.00 in cash securities. I would immedi- 
ately question those in charge as to where the 
funds are kept, at what interest and on what basis 
does ARRL decide which banks will be favored 
with their deposits? 

Vs you may know, any cash reserves over 
$100,000.00 are usually suspect by Internal 
Revenue as accumulated surplus. Good reason 
must be shown as to why the amount is carried 
instead of distributed to shareholders, A penalty in 
the form of 27%% can result if a reasonable basis 
fails to exist. Does a reasonable basis exist for 
ARRL to carry funds in excess of 8100,000,00 
without distributing the rest in benefits to its 
members? I think not. Why isn't this money being 
used in the many areas of amateur radio that are in 
dire need of increased activity? My experience in 
commercial affairs leads me to conclude that 
someone's self-interest is being held in higher 
regard than that of the majority. I believe that 
from reading your comments under ARRL 
National Convention Report, ARRL Articles of 
Association Waived, etc.. that vou have reached the 
same conclusion. 

The success of your magazine is an indication 
that the masses of dedicated amateurs agree. They 
can see what is happening to their dollars and 
privileges. How could ARRL ever give its blessing 
to incentive licensing and still maintain the inter- 
ests of the majority; of amateurs? 

J have compiled a list of some objectives which 
I believe would be in the best interests of the great 
majority of hams. Unfortunately, I also believe 
that ARRL would not lend support to them. They 
are: 

1. Devising of a plan of incentive licensing 
which would return the frequencies lost, and 
further grant new frequencies for those who 
have advanced past General. 

2, Establishment of effective representation in 
Washington, Greater privileges for the ama- 
teur can only come through the FCC and 
Congress; without their help we are power- 
less. How creative effort has never been 
utilized in this area previously is beyond 
belief. The possibilities are endless. It is not 
hard to foresee the day when amateurs could 
be compensated directly by the Government 
in return for the maintenance of an emer- 
gency communications network. Govern- 
ment surplus equipment could be offered 
directly to the amateur at reduced costs. 
These ideas may be "way out" to some, but 
think a moment about the great advantages 
now being extended to other special interest 

f roups, 
mproved public relations, 
4. Recruiting drives* 

1 cannot imagine how an educated populace 
like the amateur radio community could remain 
silent for so long a period of ARRL inactivity. The 
ARRL leadership structure is, in mv opinion, 
guilty of gross mismanagement. 

Like yourself, Mr. Green, I believe that a 
change in ARRL thought and direction would 
mean greater growth for amateur radio. 

I believe tne time has come for an all-out drive 
to elect a complete slate of new directors who 
share our thoughts and opinions. Your magazine is 
one of the few vehicles available for such an 
objective. I strongly urge you to consider such a 
campaign. If I can be of any assistance, please do 
not hesitate to contact me* 

Sheldon A. Harris WB9BCZ 

Attorney at Law 
Chicago iL 60603 



What Price ARRL? 

Dear 73, 

I have been reading your magazine for a few 
years now and 1 have yet to become tired of its 
content. I was disgusted with the others within a 
year. They always have the same articles in them. I 
always look forward to 73 arriving at my shack. 

I have been reading with interest your feature 
"Leaky Lines." One paragraph of it is worth a 
whole issue of QST. The boys at ARRL have been 
in amateur radio so long they have forgotten what 
it's like to be a relatively new ham like me of only 
seven years. In my opinion, it's the ARRL that is 

stagnating, not the general ham population. They 
beat down any idea for improvement which is the 
least bit contrary to their way of thinking, 

I read the minutes to the May board meeting in 
QST after reading them in 73 and QST's version is 
funnier. How these people can waste so much time 
and money doing absolutely nothing is unbeliev- 
able. I feel sorry for those who join ARRL 
expecting betterment of amateur radio and then 
seeing it spent on those worthless board meetings. 
You tell me to support ARRL because it's the only 
national organization we have. By joining I w + ould 
support this clown circus in Newington. No sir! I 
won't give them any more of my mones 

They sit and argue about putting info on 
repeaters in the handbook, when there should be 
no argument at ail. Then QST has the guts to ask 
for articles on the subject, which thev don't pav 
for, and yet they have a PAID technical staff at 
ARRL. What are they doing? Dusting on tiie spark 
rigs in the museum? 

Any outfit can print handbooks, logsheets, and 
DX maps. And Wl AW ought to be in the center of 
the country, not sitting out on the east coast. They 
even had to start up a code practice station on the 
west coast because nobody could hear that one 
squeaking out east. As for FCC petitions, anyone 
can get one up so who needs ARRL? 

Jerome Grokowsky WA9HCZ 

Pulsars, Quasars, and the Like 

Dear Sir, 

As Mr. Hoisington J s article was, to me anyway, 
a rather controversial one, and perhaps inaccurate 
here and there, readers may find additional com- 
ments interesting. 

The subject matter is very tricky and I only 
wish I were capable of understanding more about 
these seemingly basic laws. I recall fighting my way 
through a quantum mechanics course onlv to 
find electric fields are quantized, toot That's where 
I stopped! 

Your magazine is very enjoyable, and has stimu- 
lated me to the point w r here this is the first letter 
I've written in response to an article in any maga- 
zine. 

Ed Schweitzer 

Dear Sir* 

The article by Bill Hoisington, K1CLL, in the 
September 1969 issue of your magazine reflects 
the work of a good inquisitive and active mind, and 
I certainly agree that satisfactory explanations of 
quasars and pulsars are in short supply. 

I recall a book written by a Mr. Dolbear, 
entitled Matter Motion and Ether, The book was 
written around 1 900, and Dolbear was a physicist 
at a university in this country, perhaps at Duke, 
but probably at Tufts University. It has been five 
or more years since IVe seen the book, and it is not 
now available to me, and I apologize for the scanty 
details on the book and its author. 

However, I recall he investigated the ether 
problem from a similar point of view, that is, 
vortex waves, or rings. 1 was intrigued enough to 
build a number of vortex ring generators and spent 
many days fascinated by their behavior. For 
example, one ring may be made to pass through 
another if they are directed on the same path but 
head on in exactly opposing directions. I also recall 
that a slight angle between the paths was sufficient 
to upset this amusing effect. Note that this is 
rather contradictory to the behavior of electro- 
magnetic radiation. 

After reading elsewhere that soldiers during the 
Civil War were reportedly observed to fall as the 
result of cannon blasts far from the soldier (this 
refers to some soldiers whose position was not 
coincident with the trajectory of the projectile), I 



128 



73 MAGAZINE 



experimented with devices capable of producing 
much larger vortex rings than the coffee can 
devices could* I succeeded in extinguishing candle 
flames at 20 to 30 feet ranges with a ring about 
four or five inches in diameter. This was done in a 
college dormitory where drafts perpendicular to 
the propagation direction were uncontrollable, 
That the drafts Interfered has more significance 
than making it difficult to aim my generator at a 
small, distant target. 

Consider the experiments of Michelson and 
Morley in California around 1900, The ether 
mystery was one target of their classic and famous 
interferometer experiments, I refer to Studies in 
Optics by A. A, Michelson, where he describes the 
details of his work in relation to the controversial 
theories of the day. Any ethereal wind* perhaps as a 
result of the earth speeding along its orbit, should 
cause differences in propagation times along the 
legs of the interferometer. No differences were 
observed* a result strongly supporting the no- 
medium-necessary camp. Please recall how the 
cross drafts upset my vortex ring experiment, and 
note the conflicting but, I think, explained results. 

The ether matter deserves questioning on other 
bases, but the proof is in Michelson's experiments. 
Basing theories on the postulation of an ether will 
lead to results as disastrous as the results for 
planetary motion based on an earth -centered sys- 
tem. 

May I also comment on Mr. Hofeington's 
discussion of the unacceptable nature of the dual 
nature of light, i.e., waves and particles. In quan- 
tum mechanics, the wave-particle problem is 
attacked from a probabilistic point ot view, and 
the results are in excellent agreement with observa- 
tion. For example, radiation in quanta (photons) 
and Heisenberg's uncertainty principle are results 
predicted by quantum mechanics, and apparently 
not questioned by Mr, Hoisington, 

At this point, where quantum mechanics and 
relativity are starting to merge on me, I stop. But 
the theory and confirming experiments from here 
on add more and more support to two points I f v* 
tried to illustrate, 

1 . There has never been evidence presented to 
support the existence of an ether, 

2, A dual nature is evidenced in light when 
considered in terms of our concepts ox particles 
and waves. 

I hope I am not insulting by writing that I at 
first thought this to be an April QST type of 
article, and further hope that I have not been taken 
in on a spoof, 

Edmund O. Schweitzer III WA3LPD/K9ZXE 

3507 Lancer Drive 
Hyattsville MD 20782 
Ed, Note. Mr. Hoisington is quite earnest in his 
theories. 



CW in Perspective 



Sir: 



For the last fifteen years of my life I have been 
directly involved in the field of electronics and 
radio; my duties have taken me from design to test, 
to maintenance sales and every other aspect of the 
field of electronics, not necessarily in the above 
order; a number of these years to the present time 
I have shared with amateur radio, and I must say, 
they have been most enjoyable. 

My interest has been focused lately in the 
current controversy about the latest changes in 
regulations by the regulatory body of amateur 
radio, the FCC. 1 have followed with interest the 
opinions of different sectors of the "ham popula- 
tion*' in the States, as well as reaction from outside 
the country, and when viewed individually, I think 
the arguments in favor are as strong as the 
arguments against them. 

I, however, decided to look at them from a 
different point of view... The purpose of amateur 
radio in the United States as well as in most 
countries around the world, is one of "service to 
the community " "service to society,'* and self- 
improvement of the operator, in both technical 
and mental aspects. 

The amateur frequencies in this country have 
been divided in several portions, where operations 
in one or other mode are permitted or restricted: 
mainly we can observe a lower part of a band of 
frequencies used for CW and another part being 
used for "phone" work, with some more divisions 
allowing certain privileges to certain classes of 
license. In order to qualify for them, prospective 
amateurs have to pass a test which will measure 



their ability and knowledge in the field of radio 
amateurism. 

I have been very interested in the emphasis 
being placed on CW operation, higher and higher 
speeds are required in order to qualify for general, 
advanced or extra class; presumable we are assum- 
ing that^this ability to operate the key at higher 
rates is "a service to society or a way to improve 
the operator and prepare him for a better future... 
nothing could be further from the truth, and don't 
get me wrong: I have absolutely nothing against 
CW operation per se, like I have nothing against 
radio control or RTTY or any other form of 
expressing one's preferences in the field of radio, 
but 1 do feel that the unnecessary restrictions and 
regulations placed on the amateur community by 
these laws are repressing progress and producing an 
effect completely opposite to the one originally 
intended by the FCC. Let me make this clear, 1 am 
going to submit to you very convincing arguments 
that can be checked by anybody at any time, but I 
do not propose that we do away with CW 
operations; quite the contrary, all the amateurs 
that prefer this type of operation should continue 
to do so without any restrictions of any kind, but 
the emphasis placed on it should be channeled to 
some other fields of research more useful to 
society and the country. 

For the past few months I have been research- 
ing industry, schools, and government agencies in 
the Western area of the USA, and sad as it may be, 
the consensus is unanimous, without exception; 
CW is a thing of the past, of another time, long 
gone. It seems that only the ham fraternity clings 
to it, it will not leg go— perhaps due to the FCC, 
perhaps due to the Tact that we are stagnant, more 
probably a combination of both facts, the truth is 
that CW regulations are holding down progress in 
amateur radio, it occupies a great portion ot our 
frequencies that could be used to research some 
more advanced means of communication and 
perhaps recover the leadership that we lost when 
Teletype and computers were given the job of 
transferring intelligence from one point to another. 

A Los Angeles City School official told me that 
as far as he can remember, there was only one 
school in Los Angeles that ever had a course in 
telegraphy, and that course was discontinued a 
long time ago FOR LACK OF JOBS in the 
industry to place the graduates. 

A head engineer for the telephone company 
told me that as far as he remembers, telegraphy is 
not being used nor had it been used for a long 
PERIOD OF YEARS, 

Good old Western Union representatives told 
me that telegraphy was too slow and inefficient a 
way of communication to be used any more, he 
knows of no operation in the USA that uses CW, 
and he can remember none, 

It seems to me that those are pretty conclusive 
statements, and a quick check around the country 
will show that conditions are the same. The 
question is: What are we being led to; are we 
preparing ourselves to serve the country in case of 
need; are we ready to be a service to society in case 
of emergency or are we preparing ourselves to 
provide a disservice to the community, with our 
antiquated practices; and perhaps eventually lose 
our frequencies to some other service that proves 
to have more foresight than we did. Are we getting 
ready to go to the planets and stars with our high 
speed: 25 words a minute; or should we be getting 
ready for a more sophisticated way to convey 
intelligence at millions of bits per second and 
more... 

It is time that those who represent the amateur 
community, look at the future, at the present, and 
at our activities. Since the first wireless was turned 
on, we have progressed to the fantastic speed inew 
regulations) of 25 words per minute. It is time that 
we really make some progress, it is time that the 
FCC and the members oi the regulatory bodies 
take a new look at amateur radio, the ARRL, the 
amateur publications; and all amateurs should 
express their opinions and views on the subject. 
The growth of amateur radio has come to a 
standstill, and it is our responsibility to do some- 
thing for it, to give a new challenge to our group *it 
is the responsibility of its leaders to petition the 
FCC and Congress for the necessary laws and 
regulations to make our goal possible* 

Edgar A, Romo HC2RP 

7312 Mason Ave 

Canoga Park CA 91306 



FEBRUARY 1970 



129 







• • • 






Gus 



Thr DX'er 




Tom Orr W6EIF 
249 Juanita Way 
Placentia CA 92670 




The QSL Bureau 



The Tower Manufacturer 




The Rare DX Station 




The Novice 




The General 



The DX Station's QSL 
Manager 



130 



73 MAGAZINE 




Lee Zip in WA3GGH 
1013 Melrose Avenue 
Melrose Park PA 1 9126 





Micro-Mitter compared to a Vibroplex Lightning Bug. 



micro MITTER 



• . . TEENSY-WEENSY QRP ON 40 



In the March, 1968 issue of 73, an article 
was published entitled, "Mini-Mitter; the 
Ultimate in Miniatures!" Mr. Pyle suggested 
the possibility of having built the smallest 
CW transmitter to date. Several months 
earlier, however, I constructed a complete 
CW transmitter which, with the power sup- 
ply, fits into the case that the crystal came 
in (for convenience, the crystal remains 
outside, plugging into an internal socket). 

The circuit is a typical crystal oscillator 
circuit, using a 2N2188 transistor. The unit 
was built to operate on 40 meters, but with 
proper adjustments in the LC section and 
crystal value, any low frequency can be 

obtained- The parts are strictly junkbox, 
and the smaller the better. I used a miniature 
tuning capacitor from a junked transistor 
radio, and wound the coil so the pair would 



40 M 

XTAL 




I-4V 



Fig. 1, Schematic of Micro-Mitter. L and C should 
resonate at the crystal frequency. 



resonate at 40 meters. The battery is a 
watch-type mercury cell, with its socket 
made from two pieces of sponge rubber and 
wire contacts. Any suitable glue can be used 
to hold everything together. 



GROUND 




„ ANTENNA 



HOUE5 f 
FOR 
CRYSTAL 



Fig. 2. Case layout. The case is opened on its back, 
and the battery is removed for clarity. 

To operate the unit, attach antenna and 
ground wires to their respective clips. Push 
the key down and tune the variable capaci- 
tor for maximum signal (as indicated on 
your receiver— don't worry, it won't burn 
out the front end). I haven't measured input 
or output power on the rig, but I carried on 
a QSO with a station 50 miles away. Not bad 
for something you can lose in your shirt 
pocket! 

. . . WA3GGH ■ 



FEBRUARY T970 



131 



DIMENSIONAL GEOGR 







" * 



73 MAGAZINE 



APHIC PROJECTIONS 






A MUST FOR 
REPEATER OWNERS 
REPEATER PLANNERS 
VHF ENTHUSIASTS 

OPERATORS 







r ■ 



DIMENSIONAL GEOGRAPHIC PROJECTIONS 



if 



VHF * REPEATERS * FM 1^ 



* SHACK DECORATION * 

Here is the last word in maps for 
the shack, . .three dimensional maps 
of your area. Maps are available for 
just about any area where there is 
mountainous or hilly terrain. 

These maps are 18" high by 26 
wide and are the most exact three 
dimensional maps ever made. The de- 
tail is incredible. Most maps have 
even the smallest dirt roads shown as 
welt as attitude markings for every 
100 feet and the height of taller 
mountains. Route numbers are given 
for roads; towers and other outstand- 
ing physical features are shown. 

Using a repeater or planning one? 
You'll need this accurate 3D map to 
see your service area. Active on six or 
two meters? Use this map to back 
your rotatrng indicator. 

These maps are made of perma- 
nently molded sturdy plastic, and 
come to you packaged flat in a large 
box. 

The maps may be cut with a pair 
of scissors and glued together to form 
a large mosaic wall mural. You'll need 
a wall 15 feet high to mount all of 
California. Each map shows a north- 
south area of 75 miles and an east- 
west area of 100 miles, 

MAPS ARE $7.95 each r Postpaid! 

Send cash; check, money order to 
DGP, Box 431, Jaffrey NH 03452. 

Your maps will be sent to you 
within three to five weeks. 




Send me 
Name 



maps at S7.95 each 



CalL 



Street. 



City 



State. 



Zip 



BRUARY 1970 



133 



I I 



PROPAGATION CHART 

J. H. Nelson 

February 1970 

sun mon ruei wed thci* hi sat 

0® * ©®@© 
8 9 (/0) (ll) (22) (B) 14 



21 



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Legend: Good O Fair (open) Poor □ 



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A I m o s t a n y i n t e grated c in it it 
operational amplifier can he used to 
build this Q-multipHer. Its advantages 
are extreme circuit simplicity and a 
useful frequency range that extends 
from audio frequencies to almost all 
i-f fre quen cie s. Both t h e pea k ing fre- 
quency and Q can he made variable. 




Both vacuum tube and transistor Q-multi- 
plier circuits find wide application in im- 
proving the selectivity of transceivers and 
receivers, particularly on CW when the 
Q-multipiier is used to peak the i-f response 
following a steep-skirted crystal or .mech- 
anical SSB filter. The Q-multiplier provides a 
very narrow bandpass but if used alone does 
not provide steep skirt selectivity. When 
used in conjunction with an SSB filter, how- 
ever, the latter provides the necessary skirt 
selectivity (see Fig. 1). 




A = Next higher frequency may be useful also* 
B = Difficult circuit this period* 



Fig, L Placement of Q-multiplier after SSB filter 
provides effective narrowband response for CW 
reception. 



134 



73 MAGAZINE 




BmEl^flildfifflllil 


Multipli 


1 

ler 





John J. Schultz W2EEY 
1829 Cornelia Street 
Brooklyn NY 1122? 



The Q -multiplier described in this article 
is meant to be inserted between any i-f stage 
in a transceiver or receiver following an SSB 
filter. It can be easily switched for broad- 
band operation so it does not affect normal 
SSB operation. Since it is adjusted for unity 
gain, it does not upset any gain relation- 
ship in the i-f stages. As compared to 
vacuum tube and transistor-type Q-multi- 
piiers, the circuitry of the unit is extremely 
simple due to the use of an integrated circuit 
operational amplifier. The unit can be suc- 
cessfully used on frequencies far higher than 
those normally used with vacuum tube or 
transistor Q-multipliers up to 5 MHz or more, 
depending upon the integrated circuit used. 
The circuit can also be used at audio 
frequencies, if desired. One can also build an 
audio selectivity unit for outboard use when 
it is not desired to make internal modifica- 
tions to a transceiver or receiver. 

Circuit Description 

The Q-multiplier is constructed around an 
integrated circuit operational amplifier. 
Many such amplifiers are available on the 
market at prices starting at a few dollars. 
The main requirements for choosing a suit- 
able unit are that it have a differential input 
(inverting and noninverting inputs), and a 
single-ended output and a bandwidth suffi- 
cient for the frequency of operation. For 
example, Fairchild 70 9T ampjifiers are avail- 
able for about $3 and are usable up to at 
least 500 kHz. I built a unit using a Fairchild 
741 which is usable up to 1-2 MHz. Other 
amplifiers such as a Motorola MCI 530 can 
be used up to 10 MHz. 



e in *■ 



Rt 

-wv- 



^OUT^lN** 27 *' 




O E 



OUT 



Fig. 2. Basic type of integrated circuit operational 
amplifier with a differential input and single-ended 
output that is needed for the Q-multiplier circuit. 

Figure 2 shows the schematic of the type 
of operational amplifier which is used and the 
formula for the output voltage of an ideal 
amplifier. The Fairchild 741 amplifier which 
I used requires no external frequency com- 
pensation components. Other amplifiers may 
require a few external components for this 
purpose as specified on their data sheet. The 
frequency rolloff components should be 
chosen such that the amplifier gain starts to 
decrease just above the frequency where it is 
used as a Q-multiplier. There is no advantage 
to having the gain ' 'rolloff " at any higher 

frequency and would just make the amplifier 
more susceptible to oscillation due to a stray 

feedback path via external components. As 
noted from the gain formula, the gain of the 
amplifier depends upon the ratio of R2 and 
RL If R2 is made equal to Rl, the gain is 
unity. The Q-multiplier effect is based upon 
replacing R2 with a parallel resonant circuit 
which will present a very high impedance at 
one frequency and, therefore, maximize the 
overall gain at that frequency. Positive feed- 
back is also used to enhance the Q-multi- 
plying effect of the circuit. 



FEBRUARY 1970 



135 



INPUT O- 



01 



IK 



470ph 

{ NYTRONtCS SWD-4T0. 
ALLIED RADIO PT NO 54FQU4) 



t 



/YYV\ 



if 



SOOmmt TRIMMER 




FAIRCHJLD 
741 




01 
-))— O OUTPUT 



INCREASE 



Fig. 3. Circuit of the Q-multiplier as constructed 
for a 455 kHz i-f 



Figure 3 shows the schematic of a practical 
Q-multiplier circuit with the LC circuit reso- 
nant at 455 kHz for use in a 455 kHz i-f 
chain. Positive feedback is supplied via a 1 
kfi potentiometer. As with other Q-multi- 
plier circuits, the Q can be increased by 
regulating the feedback until a point is 
reached when the unit will break into 
oscillation. The Q-multiplying effect is most 
effective when components are used for the 
resonant circuit which in themselves have a 
good Q. The inductor used for the 455 kHz 
Q-multiplier is a molded type which provides 
a Q of about 55 at 455 kHz by itself. The 
circuit can multiply this value by about 50 
times or more. Another suitable inductor 
can be obtained by using only one or two 

sections from a regular 1 mH rf choke. The 
trimmer capacitor is used to set the fre- 
quency of the Q-multiplier in the middle of 
the i-f pass band. It can, of course, be used as 
a variable tuning control for the peaking 
frequency of the unit. The input resistor, 
although shown with a nominal value of 1 kST2 5 
should be chosen so that the gain of the 
overall circuit is approximately unity. 

Construction and Adjustment 

There is nothing critical about the con- 
struction of a unit utilizing the circuit 
described as long as the various lead lengths 
are kept short. The photograph, for instance, 
shows how the various components can be 
directly wired together on a small piece of 
Vector board. The board itself can be 
directly mounted near the i-f chain in a 



transceiver, receiver, or together with the 
potentiometer used for feedback control if 
the latter is panel mounted. 

If the Q-multiplier is not made tunable, 
the initial adjustment consists of peaking up 
the LC circuit. This can be done with the 
unit connected in an i-f strip and using any 
test signal centered in the i-f bandpass. The 
adjustment is best done with the feedback 
control set for minimum Q and with a barely 
audible CW test signal, The input resistor value 
should be then chosen for approximately 
unity gain. The adjustment is not difficult 
and need not be made exactly. The output 
level produced by a test signal without the 
Q-multiplier connected is noted. Then when 
the Q-multiplier is used^ the input resistor is 
chosen so that the output level remains 
approximately the same. With most transis- 
tor i-f stages, the value of the resistor needed 
will be about l-5fi. 

Bypassing of the Q-multiplier can be done 
in a number of ways in order to allow for 
normal SSB reception. If the Q-multiplier is 
made frequency tunable, it can simply be 
tuned outside the i-f bandpass. In order not 
to have the i-f gain decrease too far when 
doing this, the input resistor must be chosen 
for unity gain to take place when the 
Q-multiplier is just tuned outside the i-f 
bandpass. This will result in some increase in 
gain when the Q-multiplier is tuned to the 
center of the i-f bandpass but normally the 



- ■ 




The Q-multiplier components can be directly wired 
together using Vector hoard mounting. In this case r 
a PC board potentiometer is used to set the oper- 
ating Q rather than making it continuously variable. 



136 



73 MAGAZINE 



result will not be objectionable. Another 
way to bypass the unit is to replace the LC 
circuit with a simple resistor equal in value 
to the input resistor (as in Fig, 2). The 
switching action can be accomplished by 
using a I k!2 potentiometer for the feed- 
back control which also incorporates a 
SPOT switch. The switch must be wired such 
that the resistor replaces the tuned circuit 
when the wiper arm of the potentiometer is 
at ground potential. 

Summary 

The simple Q-muItipIier circuit described 
can be used for a variety of purposes besides 
that of improving i-f selectivity. It is useful 
for improving the Q and selectivity of a 
variety of tuned circuits as they might be 
used in FSK converters, audio filters for 
distortion tests, etc, Stagger-tuned circuits 
used in series can be formulated to provide a 
variety of bandpass shapes, often replacing 
more expensive components where bandpass 
shape factor is not important. 

The permission of Dick Gerdee of Optical 
Electronics to present this circuit, which he 
originally developed, is gratefully acknow- 
ledged. . . . W2EEY ■ 




hold on 

your 

hat! 

THE GIGANTIC 

FM 

REPEATER 

DIRECTORY 

IS 
COMING! 



It's new and fresh . . . it's accur- 
ate and up-to-date. And best of 
all — it's free to 73 subscribers. 



QUICK STOP 





NG 




Antenna Rotator 



My antenna rotator is a homebrew type 
made with a 1/3 hp motor. An early 
problem 1 notices was I hat the rotor had a 
tendency to keep turning for a few degrees 
after the stop command. So I use a discharge 
of capacitors in the motor as an electric 
brake. I also applied this technique to a 
small lathe that I bought to build 432 MHz 
cavities, It works great. When used in the 



MOTOR 

FIELD 




STAftT 

COIL 



LEFT RIGHT SW 



Ci CLOSE TO THE MOTOR 



Fig, 1 Extra contact in the go switch 



antenna rotator, the brake also provides an 
instant reversing capability. You need only 
an extra contact in the off-one switch to 
command a heavy duty relay near the 
rotator. When you are turning the antenna, 
the silicon rectifier charges a bank of capaci- 
tors, and when you stop, the condensers are 
discharged in the motor, bringing it to an 
instant halt. Put the capacitors in one by one 
until you get instant stop with your motor, 
(It is not good for dc motors.) 

• . , Jose Vicente PY2AUC* 



FEBRUARY 1970 



137 




NEW PRODUCTS 

Hi-Power Balun Offers 
Lightning Protection 

The Big Signal W2AU balun comes in 
either 1;1 or 4:1 conversion ratios, and 
boasts a full kilowatt (the California kind) 
capability, built-in lightning arrester, and a 
bandwidth of 3 to 40 MHz. Manufactured 
and distributed by Unadill Radiation Pro- 
ducts, Unadilla NY 13849. 



SJSTKL 




■**■■■ 




Crank-Up Mast has Tiltover Feature 

Tristao is now marketing a crank-up mast. 
The two-section mast goes to 49 ft and the 
three-section version reaches a towering 66 




3 ~H*L.H 



EASY 2 STEP INSTALLATION 

ft. The rotator rests right hear the ground, 
simplifying service of this mechanism. The 
complete system (called Magna-Mast) can be 
installed entirely by one man. The tiltover 
mast enables work to be done on the 



antenna from the ground, a safety feature 
which should appeal to amateurs with weak 
hearts. Both models are hot-dipped galva- 
nized steel. Drop a note to Tristao, Box 115 9 
Hanford CA 93230, 

Swan Develops Bandpass Antenna 

For VHF Bands 

The Swan bandpass antenna, developed 
for use in home television reception, has 
recently been adapted for the 2 and 6 meter 
amateur bands. Swan's bandpass antenna has 
the combined properties of constant impe- 
dance match across the entire passband of 
response, with gain superior to that of an 
equivalent-sized yagi. The antenna features a 
very high front-to-back ratio as well as 
front-to-side in both the X and Z planes. 
Match is in the order of 1.1:1, and gain 
across the entire design bandpass remains 
virtually constant. 

The Swan bandpass array uses four driven 
elements, and saturates the first director 
with virtually all of the power radiated from 
those active elements. Since the first director 
sees four driven elements at four different 
distances, it responds to the designed band- 
width , giving gain at four different frequen- 
cies, hence the bandpass response. Similarly, 
each dipole is matched to four separate 
frequencies, giving a constant impedance 
match across the design bandpass, 

The advantages are: 

• Controlled bandwidth response 

• Controlled bandwidth impedance 

• Rejection of undesired frequencies and 
noise above and below desired bandpass 
response* 

• Unidirectional response 

• Improved signal-to-noise ratio 

• Greater gain than the yagi array for the 
size 

The bandpass antenna is a product of the 

Swan Antenna Company, 646 N, Union St., 

Box 1122, Stockton CA 95201. 

Portable Checker Tests FET Gain, Leakage 

The Model FT155 is an FET tester 
designed for easy use by technicians. Field- 
effect transistors, like vacuum tubes, cannot 
be checked out on a conventional transistor 
tester. The FET is measured like a cold 
vacuum tube and requires charts that 



138 



73 MAGAZINE 





HAM 
V-OJW 



Name 
I QTH 
' City. 



State 



Zip_ 



I 



on nnn ' REDLINE - Jaffrey -nh .03452 

OHMS/™ LT ' ' O""™ ' ™™ V " 

The only low priced ° h ™ 1K.1W, I.2M. 12M flU/lf J ADC 

V-O-MwithaSOOO 2^ m ^= "2 5 «* 52' 5S° *i" 011 

vdc range! dB: 0,14,28,34,40 



Ua 



dc volts; 2.5, 10, 50, 250, 500, 5000 

ac volts: 10, 50, 250, 500 @ IK/volt No taxes anywhere Plus 9Qt shipping 



measure the gain in transconductance and 
leakage in different terms than a regular 
transistor. Use is not limited to the service 
trade but is expected to fill the need of the 
many industrial technicians and engineers 
who can now test transistors but cannot 
check the FET. Sen core, fnc\, Addison IL 
60101. 





12V Power Transistors for 450 MHz FM 

A chain of balanced-emitter rf power 
transistors is capable of providing 1 2W in the 
450 MHz band with a 12V supply. The new 
transistors, 2N5644 through 2N5646, are 
intended for use as power amplifier stages of 
mobile transmitters in the UHF FM band. 
The 2N5646 family is supplied in the pop- 
ular 3/8 in. ceramic stripline opposed- 
emitter package. Wide, low-inductance leads 
provide easy design and adjustment, especial- 
ly in broadband circuitry. 

An important feature of the new transis- 
tors is their balanced-emitter construction: 
Each unit is composed of many monolithic 



transistors in parallel, with a thin-film 
Nichrome resistor in series with each emit- 
ter. If current should increase in any one of 
these transistors, the rise in voltage across 
the emitter resistor will decrease base-to- 
emitter voltage, reducing the current flow. 
The equivalent parallel resistance of all the 
resistors is very low. hence does not cause 
significant degeneration. Because of the 
balanced-emitter construction, these transis- 
tors are very resistant to damage from 
mismatched loads or detuning. Motorola 
Semiconductor Products fnc\, Box 20924, 
Phoenix AZ 85036. 




The Motorola 2N5646 rf power transistor has an 
output of 12 W in the 450 MHz hand with a 12V 
supply. Balanced emitter construction makes 
device resistant to detuning and mismatching. 



Semiconductor Book in the Printing 

The just-released Motorola Semicon- 
ductor Data Book (Fourth Edition) provides 
specifications on all ElA-registered semicon- 
ductor devices, and complete data sheets on 
all discrete semiconductors manufactured by 
Motorola (3626 types). The 2160-page hard- 
bound and fully indexed book also includes 
useful selector guides, package and applica- 
tion information, and vital semiconductor 
statistics. Motorola Semiconductor Products 
Inc.. PO Box 20912. Phoenix AZ 85036. 



FEBRUARY 1970 



139 



■ 



REGUL. PWR SPLY FOR COMMAND, LM, ETC. 
PP 106/U: Metered. Knob adjustable 90 270 v up 
to 80 ma dc; also select an AC of 6 3 v 5A t or 126 
v 2Vt A or 28 v 2*/> A. With mating output plug & 
all tech data Shpg wt 50#„. .„.„*.. 19*50 

BARGAINS WHICH THE ABOVE WILL POWER: 
LM (*) Freq. Meter: 125 20 mhi, ,01%, CW or 
AM, with serial matched calib, book, tech. data, 

mating plug Checked & grid 57,50 

TS 323 Freq. Meter: Similar to above but 20 480 

mhi. .001% With data 169.50 

A.R.C. R11A: Modern Q 5ef 190-550 khz... 12.95 
A.R.C. R22: 540 1600 khi w/tuning graph. ..17.95 
A.R.C. R13B: 108 132 mhz w/tuning graph. 27.50 



HIGH-SENSITIVITY 
WIDE-BAND RECEIVER 

COMMUNICATIONS. . .BUG DETECTION 
.. .SPECTRUM STUDIES 

38-1000 MHZ: AN/ALR-5 consists of a brand- 
new Tuner/Converter CV-253/ALR in original 
factory pack and an exc. used, checked OK & 
grtd.. main rcvr R-444 modified for 120 v, 
50/60 hz. The tuner covers the range in 4 bands 
and each band has its own Ant. input plug 
(type N). Packed with each tuner is the factory 
checkout sheet. The one we opened showed 
SENSITIVITY: 1 ; 1 uv at 383 mhz, 0.9 at 133 
mhz, 5 at 538 mhz, 4V4 at 778 mhz, 7 at 1 ghz. 
The rcvr is actually a 30 mhz IF amp I. with all 
that follows an IF r including an S meter. Has 
Pan, Video & AF outputs. Has a calibrated 
attenuator in 6 db steps to -74 db, also AVC 
position. Select pass of ±200 khz or ±2 mhz. 
AND SELECT AM OR FWI! We furnish Hand 
book & pwr-input pl ug, alt for . . . $275.00 

R-390/URR Rcvr: Collins xtl-synthesizing drift- 
less receiver, grtd 100% perfect 795.00 



SP-600*JX{ # ) Rcvr: 0.54 mhz, the popular 
late-type Hammarlund Super-Pro, aligned. grtcL 
exc. physical condition too, with book . 325.00 



VERSATILE PLATE & Fl LAM. TRANSFORMER 
Depot Spares for SP-600-JX: PrL 95/105/1 17/130/ 
190/210/234/260 v 50/60 hz. Sec. 1: 305-0-305 
v 150 ma. Sec. 2: 5 v 3 A. Sec. 3: 6.3 v 5A. 
Sec. 4: ?Y* v, 3/4 A. Sec % 5: 7% v, 1% A. Legend 

for pins fa plainly marked. "Harm, sealed 2.95 

Add posta ge for 14 lbs, and 204 insurance. 

We probably nave the best inventory of good 
lab test equipment in the country. Scopes, 
Signal Generators, VTVfVTs, DVM's, RFl 
Meters, etc., etc. But, please do not ask for 
catalog! Ask for specific items or kinds of items 
you need! We also buy! What do you have? 
How much do you want for it? 



R. E, GOODHEART CO-, INC. 

Box 1220 GC, Beverly Hills, Calif. 90213 
Phones: Area Code 213, Office 272-5707 

Messages 275-5342 



WE PAY CASH 
FOR TUBES 





ics, Inc. 



303 Wesl Crescent Avenue 
Allandale, New Jersey 07401 



Magnetic Latching RF Relay 

Development of a new single-pole, 
double-throw magnetic latching coaxial relay 
has been announced by Dow-Key. The relay, 
which measures approximately 2 x 2 x 3/4 
in., will handle SOW CW or FM, 100W PEP 
at frequencies up to 1.2 GHz. The no- 
bounce latching feature of the new relay 
makes it especially suitable for satellite and 
other applications where power consump- 
tion is of critical importance. The maximum 
vswr is 1.3:1 at 12 GHz. Coil voltage is 26V 
(dc). Dow-Key Co., Broomfield CO 80020. 




Scan Receiver has Lockout Feature 

Among the first in a new series of 2 meter 
FM receivers that provide autoscanning, the 
Kris also contains switches that allow chan- 
nels to be skipped over in the scanning 
process. 




The autosean receiver samples 7 channels, 
sequentially and continuously, and "locks 
on* 1 whenever a signal appears on one of the 
7 channels. The scan rate is 20 samples per 
second. Crystals are not included in the 
$149 price. Kris, Inc., I026B £ Washington 
A) Cedarburg WIS SO 1 2. 



140 



73 MAGAZINE 






5-Element Single-Band Beam Offers 
High Gain, Low SWR 

The ''Classic 20" is a 20 meter single- 
hand beam featuring the Classic Feed Sys- 
tem (Pat, No. 3419872). An improved elec- 
trical balance^ "Balanced Capacitive Match- 
ing/' combines with optimum spacing to 
provide maximum gain, increased band- 
width, and more efficient performance than 
other antennas of its class. The rugged 
construction typical of all Mosley beams is 
incorporated into the Classic 20: high- 
impact insulators and clamping blocks, alu- 
minum tubing, and stainless steel hardware. 
Specifications: 

Power rated: 1 kW AM/CW; 2 kW PEP SSB 
Forward gain; 9,8 dB (11.9 dB over iso- 
tropic source) 
Front-to-back ratio: 20 dB 
SWR: L5:l 
Feedpoint impedance: 52fi 

The Classic 20 is a product of Mosley 
Electronics Inc., 4610 jV # Lindbergh Blvd., 
Bridge ton MO 63042, 

Electronic Keyer has Multiple Functions 

In addition to providing perfectly formed 
and spaced characters when used with a 
paddle or squeeze key, the EK-38 "Elec- 
tronic Fist" provides semiautomatic keying 
with a straight key or a "bug" for use 




on-the-air or as a code practice oscillator. 
Power supply, sidetone oscillator, and 
speaker are built into the small attractive 
cabinet. Sidetone pitch and volume controls 
are provided as well as momentary and 
locked TUNE switches. A jack is provided 
for an external manual standby key. Curtis 
Electro Devices, Box 4090, Mountain View 
CA 94040. 



mayday 

urgently wanted 

TOP PRICES FOR: 

AN/SGC-1, 1A Navy Teletype 

Terminals. 
AN/SPA-4A, 4B Navy Radar 
Repeaters. 

Call collect for top offer: 
213-938-3731 

COLUMBIA 






(We have to get rid of these items 
now- 'cause we gotta have the space!) 

TAMAR 12V + MOBILE RF POWER AMPLIFIER 

This is a very compact RF Amp. Originally mfy. 
for light aircraft Frequency 118-128MC. Easily 
convened to 2 or 6 meters. Has built in transistor- 
ized power supply. Uses 1 ea. 6360; 1 ea. OB2, 
supplied with schematic. Less tubes. Special close- 
out price... .„. .89,95 

CV-253/ALR 38-1000 MC TUNEABLE 
CONVERTER 

Excel. Cone*. Late Model,, 5150,00 

COMMAND RECEIVERS 

190-550KC Q-5er Good Condition $14,95 

190 550KC A.R.C, Type R-1 1 Commercial Late 
Model Exl. Condition ...... $14.95 



540-1600KC A.R.C. Type R-22 Commercial Late 

Model Exl. Condition , __ $19,95 

1.5-3MC Marine Band Exl. Condition,. $19.95 

3-6MC 75&80 Meters Ext. Condition $14.95 

6-9MC 40 Meters Good Condition .$14,95 

TELETYPE CONVERTER TERMINAL UNIT 
AfM/FGC-IC Dual Diversity Audio RTTY Converter 

can be used with any type receiver. These are new 
and shipped in original factory crates with all spares 

* $1 49.50 

IP-69/ALA-2 PANADAPTER 
This compact unit can be used with most Ham 

Receivers after conversion. Complete with con- 
version info and schematic. Like new condition 

*«»»,, , ,m $24.95 

COLUMBIA PAYS CASH FAST 

For your surplus military electronic equipment and 

all kinds of lab grade test equipment. Write or call 
collect for top dollar. Highest cash offers in the 
country. We pay all shipping & insurance. Let us 
prove to you what we promise. 

COLUMBIA ELECTRONICS 

Dept . 7 4365 W, Pico Blvd., Los Angeles, Cal. 90019 



WE PAY HIGHEST CASH PRICE 
for Electron Tubes & Semiconductors 

Immediate Payment on Unused Tubes 

H & L ASSOCIATES 

Elizabeth port Industrial Park 

Elizabeth, New Jersey 07206 

(201) 351 4200 



FEBRUARY 1970 



141 



«v 



the permaf lex key ] 

• both ■ twin l«v*r €r itralght h«rid k»y 
in a pEvotUit 2 pJtddlt design. 

• g"rv*i initant choice of automatic 
femi-automfltic fr *tr»igKt Hand Ittying, 

• uie directly with any trammittar or 
through an «l«c Ironic key«r. 

• amp, gold diffuivd iilver contact* 
id just from 0-.060" 6- 5-50 gram*. 

• diltmctivt blue paddles arc of 
rug god G-IO Fi berg Ian epoxy, 

• cabinet ii 16 gauge polithed chrome 
iteel: 1.95* *q. x 3,73*, pa dd I** 
extend 1.25", weight app. I pound. 
9 silicon* rubber feet for stability. 

• tO0£ US made dr guaranteed for I yr. **W by mall only 

James Research company, 
20 willits road, glen cove, 



complete, 
ppd uM&caa. 



dep't: ARM 
n. y. 11542 



BRIGAR 

ELECTRONICS 

10 ALICE ST, BINGHAMPTON, N.Y. 
13904, AC 607 723-3111 

Offices and Warehouse 10 Alice Street 
COMPUTER GRADE 

ELECTROLYTIC SALE 

LARGE QUANTITIES AVAILABLE 

Minimum Order 10 pes. 
All Sizes— 5(Mea. 




SANGAMO 



SPRAGUt 






VALUE 




SIZE 


500 MFD 200 VDC 


2" 


xAW* 


1,250 MFD-180 VDC 


2" 


x4%" 


1,500 MFD 


100 VDC 


2" 


x4Yi" 


3.500 MFD- 


55 VDC 


n h ■ 


x4 1 A" 


3,500 MFD 


75 VDC 


2" 


xA'A" 


5.000 MFD- 


36 VDC 


2#< 


x4V 


5,500 MFD- 


45 VDC 


2" 


xAY*" 


11,000 MFD 


19 VDC 


2" 


x4 , / J " 


11,500 MFD- 


18 VDC 


*-j r i 


xAYi" 


12,500 MFD 


16 VDC 


2" 


x4V=" 


10.000 MFD- 


15 VDC 


2" 


x4V 


14,000 MFD- 


13 VDC 


J%M 


xAY*" 


15,000 MFD- 


12 VDC 


2" 


x4y»" 


15,500 MFD^ 


10 VDC 


2" 


x4W 


15,000 MFD 


10 VDC 


2" 


x4Y a " 


25,000 MFD- 


6 VDC 


2" 


x4y 2 " 


30,000 MFD- 


10 VDC 


3" 


x4>i' 1 


60,000 MFD- 


5 VDC 


3" 


xW 


20,000 MFD- 


15 VDC 


2y 3 "x4y/ 


15,000 MFD 


15 VDC 


2%' 


'X4 1 /," 


35,000 MFD 


12 VDC 


2" 


x 6" 


7,000 MFD 


13 VDC 


i i/i 


*x4 f /i" 


3.000 MFD- 


25 VDC 


1 jA 


xAYi" 


2,500 MFD 


45 VDC 


1 m 


x4ft" 


3 P 750 MFD 


75 VDC 


2" 


x4V t " 



No CO.D. Include necessary postage. 

• JUST BOUGHT OUT ORIGINAL CASE FOR 
CB RADIO, Includes mtg bracket for mobile 
use & slide-in chassis. Holes pre-punched for 
power supply transistor & power cord* May be 
used for mobile power supplies, P,A. system or 
speaker box or many other uses. Size - 3W* H x 
7" W x 834" D. Weight 3 lbs. Original cost 
$9.95. Our price , $1.95 

MIN ORDER $5.00 FOB Binghamton 




it Price^S2 per 25 words for non-commercial ads; S10 
per 25 words for business ventures* No display ads 
or agency discount. Include your check with order. 

<tr Deadline for ads Is the 1st of the month two months 
prior to publication. For example: January 1st Is the 
deadline for the March issue which will be mailed 
on the 10th of February. 

if Type copy. Phrase and punctuate exactly as you wish 
it to appear. No all-capital ads. 

it We will be the judge of suitability of ads. Our re- 
sponsibility for errors extends only to printing a cor- 
rect ad in a later Issue. 

it For $1 extra we can maintain a reply box for you. 

it We cannot check Into each advertiser, so Caveat 
Emptor * - * 



RTTY PICTURES FOR SALE. Vol. 1 -51.00; Vol. 
2— $2,00. Audio and perforated tapes available. 
W9DGV, 2210 30th Street, Rock Island IL 61201. 



HAMFEST. Announcing the 8th Annual WCRA 
Mid-Winter Hamfest, February 15, 1970 at DuPage 
County Fairground, Manchester Rd., Wheaton IL. 
Open 9 a.m. to 4 p.m. Tickets $1,50 at the door. 
Some space available for your own table. Further 
info write Box QSL, Wheaton IL. 

T.O- KEYER A-1 condition, $20. New paddle for 
keyer, $10. Both $25.00, Michael Windolph, 3649 
E. 65th St„ Cleveland OH 41 105. 

SELL SB300: with SSB-CW-AM filters and 2 meter 
converter, S200 or best offer. HX-20, $95. Gary 
Tater, 40 West St, Leominster MA. 



SWAN 250 with AC supply and Shure 444 mike. 
All mint condition, $250 FOB, No trades. 
McCormack, 5008 N. Carlyn Spring Road, Arling- 
ton VA 22203. 



DRAKE R-4A, T-4X, and AC-3. Perfect condition. 
All three for $400, TH-6, Cliff Dweller and Ham 
M.Alt three for $150. Also Misc. accessories. All in 
great condition, Stan Towne, 878 Thackery, High- 
land Park IL 60035 (312-433-4472). 



TOUCHTONE DIAL equivalent from Denmark. 
Ten button, convertible to all twelve in a minute 
with data included, Beige, except green and white 
while they last. 12 vdc required for oscillator 
operation. $15.00 postpaid USA. WB6WIM, 
6606 5th Street, Rio Linda CA 95673. 



142 



73 MAGAZINE 






COLOR ORGAN KIT, three 200 Watt Channels- 
$7.50; cabinet— $8,50; power supplies— $2.75 to 
S8.50; ceramic capacitors— $.10; dual flasher 1000 
Watt-$3.98; 1000 resistors, 1/2 Watt, 1/2" leads- 
$2; TV cheater cord-S.25. Catalog. Murphy, 204 
Roslyn Ave,, Carle Place NY 11514. 

SUPER GAIN (R) ANTENNA much gain, makes 
exciter sound like linear. See pgs 8 & 144, Oct. 73. 
GUERILLA (RJ high efficiency ant. See pgs 57 & 
1 13, June 73. 



DAYTON HAMVENTION April 25, 1970: Spon- 
sored by Dayton Amateur Radio Association for 
the 19th year. Technical sessions, exhibits and 
hidden transmitter hunt. An interesting program 
for XYL, For information, watch ads or write 
Dayton Hamvention, Dept S, Box 44, Dayton OH 
45401. 



GREENE. . .center dipole insulator with. , .or 
without balun. . .see 73, November '69, page 107, 

RAGS HAMFEST Syracuse, New York, April 12, 
1970 at Song Mountain, Box 88, Liverpool NY 
13088. 



FOR SALE; HEATHKIT Apache transmitter and 
Mohawk receiver. Will sell both for $300 plus 
shipping. Write: fl/L Albert, Box 12, Andover ME 
04216/ 



GET YOUR "FIRST!" Memorize, study-"1970 

Tests-Answers' 1 for FCC First Class license, plus 
"Self*Study Ability Test," Proven. $5.00. 
Command, Box 26348-S, San Francisco CA 94126. 



ROCHESTER, N. Y. is again Hamfest, VHF meet 
and flea market headquarters for largest event in 
northeast, May 16, 1970. Write WNY Hamfest, 
Box 1388, Rochester, NY 14603 



RTTY GEAR FOR SALE. List issued monthly, 88 
Of 44 MHy torroids 5 for $1.50 postpaid. Elliott 
Buchanan St Associates, Inc., 1067 Mandana Blvd., 
Oakland, California 94610. 



73 IS AVAILABLE to the blind and physically 
handicapped on magnetic tape from: SCIENCE 
FOR THE BLIND, 221 Rock Hill Road, Bala 
Cynwyd, PA 19004. 



'TOWER HEADQUARTERS!" 11 brands! Heights 
aluminum 35% off! Strato crank-ups, low costl 
Rotors, antennas and gear discounts, Phone patch 
$11.95. Catalog— $.20 postage. Brownville Sales 
Co,, Stanley, Wl 54768. 

RG8U FOAM COAX-fresh, 10* per foot-any 
length. PL259S)239 40* each, 15/$5,00, UG175 
9/$ 1.00. FOB. Monte Southward, Rt, 1 A, Upper 
Sandusky OH 43351. 



oscillator/monitor 

• fnaka-s an audible ton* to monitor 
th« RF of any CW tram mi tier from 
lOMw to I Kw 6- lOOKc to lOOOMc, 
using only in8' pickup «nt*nna. 

% can b# »*lf-trigg»r»d for cod* 
practice or the totting of •olid 
state componont* and circuits. 

• aids in tuning up €r tatting RF 
oicillator and power circuits. 

• 4 transistor, 2 diod* circuit, 
ip«alc*r, ton* adjust, AA peneail, 
toit laadi, 6" ant,, Gr magnetic ba»«. 

• cabinet it 16 gaug* black Cr clear 
anodilvd aluminum, 3,4 k 2.3 a 1.2* 
US mad* &• guaranteed for I year. 



MTj complete, 
ppd uia Aeon, 
send a chock or m.o. 
sold by moil only 



James Research company, dep't: AR-M 
20 willits road, glen cove, n. y. 11542 



NEW G&G CATALOG! 

MILITARY ELECTRONICS 



24 PAGES, crammed with Gov't Surplus Electronic Gear - the Biggest 
Bargain Buys in America! It will psy you to SEND 25c for your copy - 
Refunded with your first order, 

BC-645 TRANSCEIVER 15 tuoea, 43$ to 600 lie. 
Easily adapted for 2 way voice or code on Ham. 
Mobile, Television Experimental, tad Citizen s 
Band ft. With tubes, less power supply £- - **m 
in factory carton, BRASDNEW ^lO.yO 

SPECIAL PACKAGE OFFER; BC-54S Transceiver, DyoamOtor and ail 
accessories, Including mounting, UHF Antenna Assemblies, control box, 
complete set of connectors and plugs, **#** **a* 

Brand New $ZO.V5 




R-ll COMMAND RECEIVER ARC 190-550 Kc. Commercial 
laic model. Excellent Condition *•.,,.«--.-•-., 



$12.95 



R-4/ARR-2 RECEIVER 234-258 Mc* Tunable,, complete with 11 tubes 
BRAND NEW, including dyna motor ,.,,,,,., ************* t9*95 




BC-659 FM TRANSMITTER/RECErVER 
2T to 38.9 Mc. Xtal control on any two pre- selected 
channel a, BO channels. Complete with 13 tubes 
speaker, meter. 15x12^x6 |", Cll Ki\ 

VIBBATOR POWER SUPPLY for above, 6V, 12V or 
24V (specify when ordering}. Like New,, ,, $6,95 

McELROY AUTOMATIC KFYER Suitable for keying transmitter or for 
code practice. Ha* photo-electric cull and sensitive relay, #11 na? 
110 V B0 cycle AC, Complete with tubes, Excellent Used *pl2«V*7 

PE-219 BATTERY CHARGER Charg* one or two 6V batteries at 7 amps, 
from 6, 12 or 24 volt source. Uses one pluz-ln vibrator. Complete with 
10* power cord, En metal case 11 x 10 x 5§" deep* m m r\ r 

Weight 40 lbs. Signal Corps equipment, NEW,, $4.95 

TELEPHONE TYPE RELAY Made by J, H, Bunnell, has adjustable 
sensitivity. 150 ohm coil. Size 3| % 4 a 7 j", Shpg wt 3 lbs. NEW $3*95 

BC-605 INTERPHONE AMPLIFIER Easily converted to home or office 
intercom system. Uses piir of 1619 tubes, delivering 10 waits of audio 
power. Brand New $2,95 Excellent Used $1.96 



Rdnfe 

RECElVfRl, 
190-550 KC. 

16 mc. . ♦ ♦ . . 

**' 1 Mc » + * » * 
i.3 3 MC. 
TRANSMITTER! 

9.1-7 Mc. 
7-9.1 MC, 
2 11 MC. 
3-4 MC, 



SCR-274-N, ARC-5 COMMAND SET HQ! 



1 m -i « > 



Come late with Tubes 
BC-451 

BC-454 

R 25 

Complrte 

- BC-4S7 . . 

D w ■ "w 3 B 

- BC-459 . . 

, T.lt 

. T-19 



wim 



Uttd 

I 

tI6.9ft 

tie. so 

S14.9S 

Tuo*s 

t 6.9S 

}S*5 
iy.ss 



t,lk# 
New 

S23.SQ 

S19 SO 
S179S 
S19.50 

1 a. 95 

I 9.95 

itB.sn 

t 9.9S 

S12.SO 



BRAND 
NEW 

. 427 50 
V22 ^O 
121-50 
121- SO 

111 95 

112 95 
. 123.50 

11 1 9S 
IIS. 99 



TEHMS: 25% 
Minimum order 



Deposit with order, balance CO. D, -or- Remittance i n jyi^ 
$5.00 F.O,fi. NYC. Subject to prior sale and pric. change 

G&G RADIO ELECTRONICS COMPANY 

AT Warren St. (2nd Fl.) New York, N.Y. 10007 Ph. 212-267-4605 



**— ^— 



GET MONEY 

Guaranteed top money for any piece of surplus 
equipment. Payment in 24 hours. We afso pay ship- 
ping insurance. CaN cofleci or send list for quick 
quote, SPACE ELECTRONCS CORP. 11 Summit Ave 
East Paterson T New Jersey, (201) 791^5050 



FEBRUARY 1970 



143 



AN/ART-13 100-WATT XMTR 
11 CHANNELS 2 to 18.1 Mc 

2001500 Kc 



Collins Autotune Trans- 
mitter; extremely stable 
and suited for side 
band. Written up in 
QST Oct. issue, 1963, 
These are in boxes & 
crates as received from the Gov't & we will ship 
them out 'as is" with no guarantee. They are 
supposed to be complete & with tubes. We are 
not even going to open the boxes and wifl 
simply stick a label on them and ship them out. 
We must make room for incoming material and 
our loss is your gain, 
#ART-13 $15.00 




HAMWIARLUND APC CAPS 

Midget styte, brand new, 4,5-100 

mmfd. 

3/S1.00 12/S3.50 

APC GRAB BAG 







Unused assortment of various sizes and styles. 

Thousands on hand Si bargain priced. 

5/ST.00 3O/S5.0O 

TOROIDAL CORES 

Insulated powdered iron core about the si2e of 
25«f piece. Very low inductance, hi-freq. Wind 
your own transistor xfmrs. 
kA 70. . .5/S1.00 30/$5.00 

PH0T0FLASH TRIGGER XFMR 

Thordarson #22R44 brand 
15KV pulse, With spec sheets, 
022R44. . ,$1.75 each 



new, produces 

10/S15.00 




RF FERRITE CORE CHOKE 

H impermeability, ultra midget style, 
coated for moisture resistance, color 
coded. Used in xmtrs, receivers, convert- 
ers, TV -peaking. Brand new, worth 40<2 
each. Assortment of 1.8, 270, 330 uh. 
Pack of 30. $12.00 value. 
#A-71. . 30/S1.00 180/35.00 

TRANSISTOR MOUNTING PADS 

Round fibre glass insulating pads, used under 3 
legged TO-5, TO-18, etc. Raises and insulates 
transistors from PC board. Permits longer leads 
to be used with less danger of heat destruction. 
Adds professional touch to> finished circuits. 
Bag of 50 ore-drilled pads. 
#A-3. . .50/S1.00 30Q/$5.00 

SILVER MICAS 

Misc. assortment of CM ^S* tfK^ 5 ^ 

type small silver micas. 

Supply varies & will give a 

mix of available on-hand 

stock. Unused, long leads, 

standard codes stamped on^^ 

par \\ ^^ 

#A-4 . 30/$1.00.180/$5.00 

2 METER ARC-3 

Just uncovered a batch of the famous ARC-3 
rcvrs & xmtrs with all tubes. Range 100-156 
mc, 8 xtl channels. Cheap way to get on 2 
meters, CD nets, MARS nets, etc. With conver- 
sion details. 
Rcvr 515/Xmt r 515 B oth for $25 

Above equipment on fund, ready m ship. Terms nei 
cash, fob Lynn. Mass. Many other unusual pieces of 
military surplus electronic equipment arc described in 

our catalog. 

Send 25^ for catalog #70 



JOHN MESHNA JR. 

19 AILCRTON ST„ LYNN, MASS. 01904 
P. O. BOX 62, E. LYNN, MASS. 01904 




m 



WORLD RADIO has used gear with trial terms- 
guarantee! 99'er-$79.95; 91 0A-S1 79.95; 
SR150-$299.95;HW10-$129.95;HW32~$89.95; 
Swan 400/420-S299.95; Swan 250-8229.95; 
D uoBander 8 4-$ 109.95; 7 5 3-$ 129,95; 
NC200-S249.95; SB33-S 199.95; Galaxy 
Vmk2-S2 79.95; Ranger 2 -$149,95; 
200V-S399.95. Free "blue-book" list for more. 
Write WORLD RADIO, 3415 West Broadway, 
Council Bluffs I A 51501. 

TECH MANUALS-R 390, R-390A, OS-8C/U. 
$6.50 each. Many others. List 20d. S. Consalvo, 
4905 Roanne Drive, Washington DC 20021. 

TR-4, AC SUPPLY, Best offer. Will hand deliver 
Ohio or adjacent states, Gordon Wolford WB8CKP, 
318 South Adams, New Carlisle OH 45344 
(513-845-9461). 

BEAUTIFUL surplus 3% inch round D'Arsonval 

meter movements, Westinghouse type NX35 0-1 
mil basic with interna) shunts and scales reading 
0-50, 0-1 50, 0-250, and 0-500 mA. Individually 
tested, $3.50 each postpaid in U.S. No COD's. S. 
Brown, PO Box 183 r Hemingway SC 29554. 

WANTED: KW plug in coils r Johnson or B&W 

Swinging and fixed center link types, link assem- 
bly, jack bars. Will pay cash. W. Allen, 1376 
Meadowlark Drive, Pittsburgh PA 15243. 

SELL MODEL 19 Teletype set, $25.00. Pick up 
only. Also sell sideband engineers SB-IL 1 kW 
linear $65.00. W2AH, 151 Rock Creek Lane, 
ScarsdaleNY 10583. 



WANTED: RECEIVERS 8503-85068^85-7-8510- 
3001A-3002A~128av-Write Box 8352, Savannah 
GA 31402. 

HAMMARLUND SP-600 (R 274) receiver. CV-591 
A/UUR sideband converter for the SP-600. Apache 
TX-1 transmitter. SB-10 sideband converter for 
TX-1 Collins speaker, spare parts, tubes, all inter- 
connecting cables w/wiring hook-up diagram, key, 
mike, and all manuals. $500 for the lot, will not 
divide. Fred Bancroft, c/o Cochise College, Douglas 
AZ 85607. 



CHRISTIAN Ham Fellowship now organized for 
Christian hams who wish to fellowship with other 
Christian hams. Request free information how to 
witness to other hams. Christian Ham Callbook $1 
donation. For free details on organization write 
Christian Ham Fellowship, PO Box 218, Holland 
Ml 49423. 



5 x 8" PC BOARD, 1542 labeled solder points. 
Twin-tracks, 39 rows, 3 power loops, YOURS, 
postpaid. $2.95 with order No. 1-2-1000, Bert 
Adams Enterprises, PO Box 101, Miami FL 33152. 

NOVICE THREE-BAND DOUBLE INVERTED 
VEE: Tuned assembled SWR. Under 1.5-1 
15-40-80 Novice bands- W3FQJ Design, $15,75* 
Antenna Products, Box 276, Warrington, PA 
18976. 



144 



73 MAGAZINE 



LIBERTY 
PAYS 



MORE! 



WILL BUY 
FOR CASH 

ALL TYPES 

• ELECTRON TUBES 

« SEMICONDUCTORS 

• Military Electronic 

Equipment 

• Test Equipment 



WIRE, WRITE, PHONE COLLECT! WE PAY 
FREIGHT ON ALL PURCHASES WE MAKE 



LIBERTY 
OFFERS 



MORE! 



PRESTEl FIELD STRENGTH ..METER 

[Model 4T4G) 

*fi Never Anything Like It! 

% / Man Can Do a Better Job 

than 3 in the Same Time! 

sic A Gold-Mine for Antenna Installers! 

Frequency Range: 40 to 230 
and 470 to 860 Megahertz. 
Calibrated outword from fO 
to 50,000 Microvolts. Nothing 
makes it easier to properly and 
speedily find the correct place 
to install TV, FM and Com- 
munication Antennas. You can 
measure and hear the signals 

with this 4 J /2 volt battery economically powered 

unit* There is nothing else like itl 

Only $120.00 FOBN. Y. 



Liberty Electronics, Inc. 




U 



$100,000 

EYE SEE" 



Guaranteed* With Spec, Sheets? 

PENNY SALE! 



O709C0P AMP 

Guaranteed/ With Spec. Sheets: 



f oirchifd 

□ 900 

a yea 

[j 910 

914 
915 

923 
925 
927 
930 
933 
944 
945 
946 
94fi 

□ 953 



■ «**■■■■-■■* 



■t4lf««B1ll 



■ - »■ - Plllll 



MONEY BACK GUARANTEE! 

Buffer ........ ,.»«,„...„*».<--. ...«*« 

3 Input jrate Nand/Nor 

Dual Two Input Gate 

Jnial Two Input Gale ........ 

Dual 3 Input Gate Nand/Nor 

■_l i\ J I 1 J I A J l_P I r t tjirnniiiTiir~TiffT" •n*"* - " * * " n 1 

Dual 1 Input GaU*. Kx pander. 

Quad Inverter . ..„..., 

Due) l Input Gate Nand/Nor 
Dual Input Gate, Expander 

Dufit -1 Input Power Gate 

Clocked Flip Flop ♦ , 

Quad 2 Input Gate Nand/Nor 
Clocked Flip Flop 1HM 
2-2 3 Input and Gate 



*»n ■ +*....._ 



»* ■■* ■ ** ■ ■»*.. 



ff .**..-... mtt 



•■i--r-iri"- J i 



EACH 

1 for 1,49 

2 for 1.98 
2 for 1,98 
2 for 1 .91 

1 for 1.69 

2 for 1 .91 

1 for I 49 

1 for 1 49 

1 for 1 49 

1 for 1 ,49 

1 for 1 49 

1 for 1 ,69 

1 for 1.49 

1 for 1.98 

2 for 1.69 



U MORE 



1.70 
1.99 



4 for 1.70 



SALE ON 

FA1RCHILD 

COUNTING 




i I 



ICs" 



Guaranteed! $JT QC 

With Spec. a for $15 

No. Description 

D 958 Decade Counter 

D 959 Buffer-Memory 

D 960 Decoder-Driver 



1 amp bod Piv 10 1 49 

RECTIFIERS for 



HIGH VOLTAGE 

1 AMP 



PiV 
□ 2000* 

Z 3000 
4000 

_ 5000 
6000 

Z 8000 

□ 10000 



SALE 
1.00 

1.35 
1.65 

I" SILICON 

3-50 RECTIFIERS 
3.95 



4000 PIV 

RECTIFIERS 

1 AMP I 49 




400 mc 

NPN HIGH POWER 
UHF TRANSISTORS 

2N3632 " w « 



IfV r FOR OUR SPRING BARGAIN CATALOG ON: 
V*f- Q Scmitondutron Q Poly Paki Q Perl* 



Ttrmi: add postage. Rated: net 30* cod's 25% 
Phone Orders: Wakefield, Mass. (G17J 245-3S21) 
Retail: :! 1 1 Albion, St., Wakefield. Mass. 



POLY PAKS 



P.O. BOX 942 
Lynnfield, Mass. 

01940 



FEBRUARY 1970 



145 



^ 



I 73 Readers' DOUBLE BONUS 

• Want info quick? Just check the box next to 
| the name of the advertiser of your choice in the 

I index below. We'll rush your name to the firm 
so you can get all the dope direct from the 
source, (Don't forget to include your name and 
address at the bottom. ) 

ADVERTISER INDEX 



D Ameco 17 

□ American Crystal 109 

□ Antennas fnc, 93 
a Arnolds 103 

D ATV 107 
D Bngar 142 
p Burghardt 81 

□ Callbook 20,91 
D Caringefla 20 

D CB Radio 109 
U Cleveland Inst, 35 
D Columbia 141 
D Dahl 109 
O Delta 87 
D Denson 121 
d Denver 109 

□ DGP 127 

D Dow Trading 109 

□ Epstlon 27 
D Essco 83 
D Freck 107 

D Galaxy II, 19 

□ Gale way 123 

D GBC America 32 
P G & G 1 43 
n Good heart 140 

□ Gordon, H. 75 
D Haf strom 97 
D Harry 91 

D Henry 4, 13 

D Hunter 107 

DH&L 141 

a International Crystal 3 

a James Research 142, 143 

□ Jan Crystal 32 

□ Jeff-Tronics 123 

□ Lewispeu! 140 

□ Liberty 145 



a Merlin Co. 107 
D Meshna 144 

□ Microflect 21 

□ Micro Z 103 
O Military 143 
Q Mosley IV 

□ National Radio 111 
D Pan ironies 97 

D Park 114 

□ Poly Paks 145 
D Quement 43 

D Radiation Products 97 
D RP Electronics 121 
D Redtine 139 
D Sams 53 

□ Sentry 46 

□ Signal One 38 

□ Stellar 9 

P Swan Antenna 79 
d Swan 29 

□ Telrex 5 

D Tower 118 
D Tristao 107 
O UFO Net 109 
D United 121 

□ Vanguard 21/27 

□ Varitronics 7, 59 
D Vibropiex 103 

O Western 103 

□ WRL II 

□ World QSL 97 



□ 73 Magazine 
Books 94,95 
Maps 132, 133 
Radio Handbook 125 
Subscription 65 



Haven 't got time to browse through the ads? 
Just put an X by the subject that makes you flip. 



L 



O Antennas 


D Nameplates 


□ Baluns 


□ Oscillators (code) 


□ Calibration/Repair 


Srvc. d Oscillators Irf) 


Q Callbook 


Q PC negatives 


D Clocks 


D Preamps 


D Coaxial Relays 


D Receivers 


O Code tapes 


Q Receivers (FM) 


a Components 


□ Surplus Elec. 


□ Converters 


□ Test Equipment 


□ Crystals 


a Towers 


D Diodes 


i J Transceivers (FM) 


O DX 


n Transceivers (VHF) 


Q Equipment dist. 


Transceivers (SSB) 


a Filters 


Transformers 


D Integrated circuits 


□ Transistors 


D Keys, Keyers 


□ TV /Fax 


H Linears 


a Vacuum tubes 


MAIL TO 73 Inc. 


, Peterborough IMH 03458 


Nam* 1 






r a n 


Address 






7T-Pp 







Check the top index for specific 
firms of interest— or check the 
lower index for the items that turn 
you on. Either way, you get the 
dope— and you get it fast. 



146 



73 MAGAZINE 




Rarely is the amateur radio fraternity offered an important 
new product with the engineered-in reliability found in 
modern professional and military communications equip- 
ment. NRCI's new NCX-1000 is one of these exceptional 
products. It was conceived and developed for radio amateurs 
by the same company that gave the Marine Corps its rugged 
solid-state AN/GRR-17 tactical communications receiver, 
that gave the Navy its versatile AN/URT-22 exciter-trans- 
mitter, and that produced the classic HRO-500 VLF/HF 
receiver. 

The NCX-1000 combines rock-solid design, exceptional 
performance, and a power punch. It's the finest solid-state, 
self-contained, 5-band kilowatt transceiver available today— 
the odds-on choice of the discerning amateur, be he rag- 
chewer or DX-er. See it now at your dealer's store, or write 
for complete details. 




For complete (and impressive) specifications and details, write: 



NATION AL RADIO COMPANY, INC. 

IVrrO/ 111 Washington Street, Melrose, Mass. 02176 (617-662-7700) 






NEW SINGLE-BAND BEAM 
FROM MOSLEY 



The Classic 2 

WITH 



EXPANDED 
CAPABILITIES 

ON 20 METERS 




Model CL-20 



DON'T LIMIT YOURSELF! 

When you install a 20 meter beam, there is only one 
antenna investment you can afford . . , The NEW CLASSIC 20 
with expanded DX capabilities, thanks to the new 
Classic Feed System. "Balanced Capacitive Matching" . 
This new array promises to be the most universally accepted 
amateur beam ever developed for 20 meters. 

TAKE A LOOK AT THE VITAL STATISTICS I 

FORWARD GAIN: 9.8 db compared to reference dipole: 

1 1 .9 db over isotropic source. 
POWER RATED: 1 KW AM/CW; 2 KW P.E.P. SSB input to the final 
SWR: 1 .5/1 or better. 
MATCHING SYSTEM: Balanced Capacitive. 
FEED POINT IMPEDANCE: 52 ohms. 

NUMBER OF ELEMENTS: 5. Aluminum tubing: 6063-T832. 
MAXIMUM ELEMENT LENGTH: 38 ft. 1-tt in. 
BOOM LENGTH: 46 ft. 
RECOMMENDED MAST SIZE: 3 in. OD. 
TURNING RADIUS: 28 ft. 
WIND SURFACE: 18.7 sq. ft. 
WIND LOAD {EIA Std. 80 MPH): 364.45 lbs. 
ASSEMBLED WEIGHT: Approx. 139 lbs, 
SHIPPING WEIGHT: Approx. 145 lbs. via truck." 

Mosley is the name. Antennas are our business. 

Designed, engineered and manufactured by hams . . . for hams. 

For detailed brochure on the entire CLASSIC LINE 

of single and multi-band beams, write. . . Dept. 198G 





Jetf <£&&»& &C 4610 N. LINDBERGH BLVD., BRIDGETON, MO. 63044